UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - N-09600

Type - Initial Exploration Plan

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

Operator - Shell Offshore Inc.

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

Not Found

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

should be addressed in an Environmental Assessment.

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

Karen Dunlap

Plan Coordinator

Description -

Rig Type -

Subject:

From:

January 9, 2012
Shell 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

September 30, 2011

Ms. Liz Peuler, Section Chief

Bureau of Ocean Energy Management

1201 Elmwood Park Boulevard

New Orleans, LA 70123-2394

Attn: Plans Group MS 5231

SUBJECT: Initial Exploration Plan

OCS-G 31507, Mississippi Canyon Block 525

Offshore, Louisiana and Alabama

Dear Ms. Peuler:

 

In compliance with 30 CFR 250.103 and NTLs 2008-G04, 2009-G27 and 2010-N06, giving Exploration Plan guidelines, 

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

Depending on rig availability operations could commence as early as May 2012.

This Plan consists of a series of attachments describing our intended operations. The attachments we desire to be 

exempted from disclosure under the Freedom of Information Act are marked ―Confidential‖ and excluded from the 

Public Information Copies of this submittal. The cost recovery fee receipt of $17,210 ($3,442 for each SL) is attached 

to the Proprietary copy of the Plan. 

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

Sincerely,

Sylvia A. Bellone
SHELL OFFSHORE INC.

INITIAL EXPLORATION PLAN

for

OCS-G 31507, Mississippi Canyon Block 525

PUBLIC INFORMATION COPY

PREPARED BY:

Tracy W. Albert

Regulatory Specialist

504.728.4652

tracy.albert@shell.com
REVISIONS TABLE to PLAN N-9600:

Date of Request Plan Section What was Corrected

Date 

Resubmitted

10/3/2011 Section 1

Section 2j

Section 6

Section9

Verify Well ―B‖ BHL (proprietary copy only)

Clarification for duration of spill

Discuss ROV survey & verify well D location.

Add CGA as OSRO

10/6/2011

10/7/2011 Section 2j Revised structure map (Proprietary copy only.) 10/7/2011

10/31/2011 N/A BOEM Requested full set of plan to deem complete 11/01/2011

11/08/2011 Section 2J

Section 9

Section 18

WCD calculation 

WCD comparison table

WCD number

12/14/2011
INITIAL EXPLORATION PLAN

OCS-G 31507, MISSISSIPPI CANYON BLOCK 525

OFFSHORE, LOUISIANA

TABLE OF CONTENTS

SECTION 1 PLAN CONTENTS

SECTION 2 GENERAL INFORMATION

SECTION 3 GEOLOGICAL AND GEOPHYSICAL INFORMATION

SECTION 4 HYDROGEN SULFIDE - H2S INFORMATION

SECTION 5 MINERAL RESOURCE CONSERVATION INFORMATION

SECTION 6 BIOLOGICAL, PHYSICAL AND SOCIOECONOMIC

 INFORMATION

SECTION 7 WASTE AND DISCHARGE INFORMATION

SECTION 8 AIR EMISSIONS INFORMATION

SECTION 9 OIL SPILLS INFORMATION

SECTION 10 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

CH4 methane

CO carbon monoxide

CO2 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

H2S 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

NOx 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

SOx 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 Area
SECTION 1: PLAN CONTENTS

A. DESCRIPTION, OBJECTIVES & SCHEDULE

This Initial Exploration Plan (EP/Plan) with appendices, including an Environmental Impact Analysis (EIA) found 

in Section 18, describes the drilling activities Shell Offshore Inc. (Shell) plans to conduct with respect to OCS-G 

31507, Mississippi Canyon Block 525. The wells proposed in this Plan are A, B, C, D and E. The wells will be 

drilled and temporarily abandoned (cement plugs and corrosion cap) 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 BOEM regulations.

Shell‘s plan, as detailed in this EP, is to use a drillship, the M/V Noble Globetrotter or equivalent rig (the ―Rig‖), 

to drill up to five (5) new exploration wells in the Mississippi Canyon Area, Block 525 (MC 525), located 

approximately 79 miles from the nearest coastline (Louisiana), 164 miles from the supply base at Port Fourchon, 

Louisiana, and 208 miles from the helicopter terminal at Amelia, Louisiana. Water depths at the proposed well

surface locations are between 7,400‘ and 7,600‘ (Attachment 1A). The drilling activities are planned to 

commence on or about May 1, 2012 and take last approximately 148 days for the first well and approximately 

128 days for the other wells. 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 not intended to be a limitation. 

The proposed rig is a dynamically positioned (DP) drillship and is equipped with state-of-the-art drilling 

equipment and well control. It is a large, self-contained drilling vessel with accommodations for a crew which

includes quarters, galley and sanitation facilities. The rig will comply with the requirements in the Interim Final 

Drilling Rules. The drilling activities will be supported by the support vessels and aircraft as well as onshore 

support facilities as listed in Sections 14 and 15 of the EP. Shell has employed or contracted with trained 

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 525

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 Oil Spill Response Plan (OSRP) updated August 

2011, is designed to contain and respond to a spill that meets or exceeds the WCD detailed in Section 9 of this 

EP. The WCD does not take into account potential flow mitigating factors such as well bridging, obstructions in 

wellbore, reservoir barriers, or early intervention. We continue to invest in Research and Development (R&D) to 

improve safety and reliability of our well systems. All operations will be conducted in accordance with applicable 

federal and state laws, regulations, and lease and permit requirements. Shell will have trained personnel and 

monitoring programs in place to ensure such compliance. 

B. LOCATION

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

C. RIG SAFETY AND POLLUTION FEATURES: 

The rig (Noble Globetrotter or similar) will comply with all of the regulations of the American Bureau of Shipping 

(ABS), International Maritime Organization (IMO) and the United States Coast Guard (USCG). All drilling 

operations will be conducted under the provisions of 30 CFR, Part 250, 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. Primary pollution 

prevention measures are contaminated and non-contaminated drain system, and oily water processing.
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 drip 

pans and work areas, are discharged depending on if it comes in contact with the contaminated or noncontaminated areas of the rig.

1) Non-contaminated Drains

Non-contaminated drains are designated as drains that under normal circumstances do not contain 

hydrocarbons, and can be discharged directly overboard. These are mostly located around the main deck and 

outboard in places where it is unlikely that hydrocarbons will be found.

Drains within 50 feet of a designated chemical storage area which uses the weather deck as a primary 

containment means shall be designated ―normally plugged.‖ An adequate number of drains around the rig 

shall be designated as ―normally open‖ to allow run-off of rain water. Normally open drains shall have a plug 

located in a conspicuous area near the drain which can be easily installed in the event of a spill. 

The rig‘s drain plug program consist at a minimum of a weekly check of all deck drains leading to the sea to 

verify that their status is as designated If normally open they shall verify that the drain is open and that the 

plug is available in the area. If normally closed they shall verify that the plug is securely installed in the 

drain. 

In the event a leak or spill is observed, the event shall be contained (drain plug installation and / or spill kit 

deployment as appropriate) and reported immediately. 

Rig personnel shall ensure that the perimeter kick-plates on weather decks are maintained and drain plugs 

are in place as needed to ensure a proper seal.

2) Contaminated Drains

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

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

processing.

3) Oily Water Processing

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

content is < 15 ppm. The separated oil is pumped to a dirty oil tank and has to be sent ashore for 

disposal. On board the mobile offshore drilling unit (MODU) an oil record log has to be kept according to 

instructions included in the log. Any and all pollution pans are subjected to a sheen test before being 

pumped out. If the water passes the sheen test then it is pumped over board. If it does not pass the 

sheen test then the water/oil mixture is pumped to a dirty oil tank and sent to shore for disposal. All waste 

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

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

4) Lower Hull Bilge System

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

priming centrifugal pumps - one for each main pump room. The aux pumps can be pump out with the 

bilge pump but has to be lined up manually from the main pump room.

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

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

high and low levels.

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

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

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

• Portable submersible pumps

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

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

high-high alarm. They are set to a point at which the water gets to a certain point they will automatically turn 

on to pump water out in order to keep flooding under control. The pumps are also capable of being put in 

manual mode in which they can be turned on by hand. 

5) Emergency Bilge System

Main ballast pumps may also be used for emergency bilge pumping directly from the pump rooms via 

remotely actuated direct bilge suction valves on the ballast system. These valves will operate in a fully 

flooded compartment. The ballast pumps can be supplied from the emergency switchboard. 

6) Oily Water Drain/Separation System

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

overboard until oil content is <15 ppm. The separated oil is pumped to a dirty oil tank and has to be sent 

ashore for disposal. On board all drilling Units, an oil record log has to be kept according to instructions 

included in the log. The rig floor has two skimmer tanks and each is subjected to a sheen test before 

pumping overboard to ensure environmental safety. All three anchor winch windlasses have skimmer tanks 

and are subjected to sheen tests before discharge as well

7) Drain, Effluent and Waste Systems

• The rig‘s drainage system is designed in line with our environmental and single point discharge policies. 

Drains are either hazardous, i.e. from a hazardous area as depicted on the Area Classification drawings, 

or non-hazardous drains from nonhazardous areas.

• To prevent migration of hazardous materials and flammable gas from hazardous to non-hazardous 

areas, the drainage systems are segregated.

• The rig drainage systems tie into oily water separators that take out elements in the drainage that 

could harm the environment. This is part of Noble‘s initiative to be good stewards of the environment. 

The oily water separators divide the drainage system into these sections:

8) Rig Floor Drainage

The rig floor has been outfitted with a Facet International MAS 34-3 separator. The separator has coalescent 

plates that remove the solids from the drainage, and the remaining drainage goes to a skimmer tank. From 

the skimmer tank it is drained to one of the column dirty oil tank systems where it is then sent through two

separators and cleaned further to reduce oil content to less than 15 ppm.

9) Columns #3 & 4

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

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

15 ppm, then discharge the clean product to sea.

10) Main Engine Rooms

• The engine rooms have their own drainage and handling system. The engine rooms are outfitted with 

a dirty oil tank and the drainage in the tank is processed through the separator, the waste from the 

separator goes back to the dirty oil tank and the clean water (less than 15 ppm) goes overboard.

• The locations and models of the separators are as follows:

• Column #3 – Westfalia WSD-18

• Column #4 – Westfalia WSD-18

• Drill Floor – Facet International MAS 34-3
11) Helideck Drains

The helideck has a dedicated drainage system around its perimeter to drain heli-fuel from a helicopter 

incident. The fuel can be diverted to the designated heli-fuel recovery tank which is located under the 

Helideck structure.

Operating configurations are as follows: 

 The overboard piping valves and hydrocarbons take on valves are closed and locked. To unlock 

overboard or take on valves a permit has to be filled out. 

 The oily water collection tank overflow valve is closed.

 The drill floor drains are lined-up to the drill floor skimmer tank. The Skimmer tanks have a high 

alarm which sounds by means of an air horn. Before tanks are pumped out a sheen test is 

performed. Water is pump out the skimmer tanks down the shunt line. Oil containment side is 

pumped out into 550 gal tote tanks. 

 The subsurface blowout preventer (BOP) test area drains are normally lined-up to drain overboard.

 The oily water separator continuously circulates the oily water collection tank. Waste oil is discharged 

into the waste oil tank and oily water is re-circulated back into the oily water collection tank. Clean 

water is pumped overboard, which is controlled and monitored by the oil content detector, set at 15 

ppm. 

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

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

 The engine dirty oil sump can be drained down in Port column oily water separator which discharges 

water overboard from the water side and oil being pumped out into a 550 gal tote tank oil 

containment side. There is a high audible alarm on the ballast control panel. 

D. Storage Tanks - Noble Globetrotter

Type of Storage Tank Type of Tank Number of Total Fluid

Facility Capacity 

(bbls)

Tanks Capacity 

(bbls)

Gravity (API)

Fuel oil MODU 2,652 1 2,652 No. 2 diesel

Fuel oil MODU 1,743 1 1,743 No. 2 diesel

Fuel oil MODU 5,767 1 5,767 No. 2 diesel

Fuel oil MODU 4,399 1 4,399 No. 2 diesel

Fuel oil MODU 2,652 1 2,652 No. 2 diesel

Fuel oil MODU 3,250 1 3,250 No. 2 diesel

Fuel oil MODU 4,399 1 4,399 No. 2 diesel

Fuel oil MODU 2,618 1 2,618 No. 2 diesel

Fuel oil MODU 115 4 460 No. 2 diesel

Fuel oil MODU 129 4 516 No. 2 diesel

E. Pollution Prevention Measures 

Pursuant to NTL 2008-G04 the proposed operations covered by this EP do not require Shell to specifically 

address the discharges of oils and greases from the Rig during rainfall or routine operations. Nevertheless, 

Shell has provided this information as part of its response to1(c) above. 

F. Additional Measures

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

meetings. The discussion around no harm to people or environment is a key mindset. All personnel 

are reminded daily to 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 annual basis.

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

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

 Shell will use low-sulfur fuel to reduce air pollutant impacts.
Attachment 1A - Bathymetry and Surface Locations
Attachment 1B

Bottom Hole Locations

PROPRIETARY DATA
Attachment 1C

 

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

Minerals Management Service OMB Approval Expires: December 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 31507 Area: MC Block(s): 525 Project Name (If Applicable): Rydberg Deep

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

Description of Proposed Activities (Mark all that apply)

X Exploration drilling Development drilling

Well completion Installation of production platform

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

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

Installation of subsea wellheads and/or manifolds Commence production

Installation of lease term pipelines Other (Specify and describe)

Have you submitted or do you plan to submit a Conservation Information Document to accompany this 

plan?

Yes X No

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

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

Do you propose any activities that may disturb an MMS-designated high-probability archaeological area? X Yes No

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

MMS?

Yes X No

Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Drill well A 05/01/12 09/26/12 148

Drill well B 05/01/13 09/06/13 128

Drill well C 05/01/14 09/06/14 128

Drill well D 05/01/15 09/06/15 128

Drill well E 05/01/16 09/06/16 128

Description of Drilling Rig Description of Production Platform

Jackup X Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Compliant tower

Semisubmersible Submersible Fixed platform Guyed tower

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

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

Description of Lease Term Pipelines

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

N/A

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)

Attachment 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): A Subsea Completion

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31507

Area Name Mississippi Canyon 

Block No. 525

Blockline

Departures

(in feet)

N/S Departure: 1,882' FSL

E/W Departure: 1,206' FWL

Lambert X-Y 

coordinates

X: 1,331,766

Y: 10,329,562

Latitude/

Longitude

Latitude

28.46084723

Longitude

-87.96089538

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

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 

35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or 

Development Operations Coordination Document submitted for MMS approval. We use the information to 

facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of 

Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to 

respond to, a collection of information unless it displays a currently valid Office of Management and Budget 

Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the 

burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that 

burden to average 580 hours per response, including the time for reviewing instructions, gathering and 

maintaining data, and completing and reviewing the form. Direct comments regarding the burden estimate or 

any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240.

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)
Attachment 1E

OCS PLAN INFORMATION FORM (CONTINUED)

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location

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

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline

Departures

(in feet)

N/S Departure: 2,112' FSL 

E/W Departure: 7,470' FWL

Lambert X-Y 

coordinates

X: 1,338,030

Y: 10,329,792

Latitude/

Longitude

Latitude

28.46161632

Longitude

-87.94140200

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

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 

35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or 

Development Operations Coordination Document submitted for MMS approval. We use the information to 

facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of 

Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to 

respond to, a collection of information unless it displays a currently valid Office of Management and Budget 

Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the 

burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that 

burden to average 580 hours per response, including the time for reviewing 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 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240.

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)
Attachment 1F

OCS PLAN INFORMATION FORM (CONTINUED)

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location

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

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline

Departures

(in feet)

N/S Departure: 1998' FSL

E/W Departure: 3410' FWL

Lambert X-Y 

coordinates

X: 1,333,970

Y: 10,329,678

Latitude/

Longitude

Latitude

28.46121464

Longitude

-87.95403751

TVD (Feet): MD (Feet): Water Depth (Feet): 7,505‘

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 

35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or 

Development Operations Coordination Document submitted for MMS approval. We use the information to 

facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of 

Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to 

respond to, a collection of information unless it displays a currently valid Office of Management and Budget 

Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the 

burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that 

burden to average 580 hours per response, including the time for reviewing 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 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240.

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)
Attachment 1G

OCS PLAN INFORMATION FORM (CONTINUED)

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location

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

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31507

Area Name Mississippi Canyon 

Block No. 525

Blockline

Departures

(in feet)

N/S Departure: 4202' FSL

E/W Departure: 5614' FWL

Lambert X-Y 

coordinates

X: 1,336,174

Y: 10,331,882

Latitude/

Longitude

Latitude

28.467322594

Longitude

-87.94723080

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

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 

35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or 

Development Operations Coordination Document submitted for MMS approval. We use the information to 

facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of 

Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to 

respond to, a collection of information unless it displays a currently valid Office of Management and Budget 

Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the 

burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that 

burden to average 580 hours per response, including the time for reviewing 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 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240.

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)
Attachment 1H

OCS PLAN INFORMATION FORM (CONTINUED)

Include one copy of this page for each proposed well/structure 

Proposed Well/Structure Location

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

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline

Departures

(in feet)

N/S Departure: 4782' FSL

E/W Departure: 858‘ FWL

Lambert X-Y 

coordinates

X: 1,331,418

Y: 10,332,462

Latitude/

Longitude

Latitude

28.46881763

Longitude

-87.96205091

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

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 

35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or 

Development Operations Coordination Document submitted for MMS approval. We use the information to 

facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of 

Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to 

respond to, a collection of information unless it displays a currently valid Office of Management and Budget 

Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the 

burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that 

burden to average 580 hours per response, including the time for reviewing 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 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240.

MMS FORM MMS-137 (December 2008 - Supersedes all previous editions of form MMS-137 which may not be used.)
SECTION 2: GENERAL INFORMATION

A. Application and Permits

There are no individual or site-specific permits other than general NPDES Permit and rig move notification that 

need to be obtained.

B. Drilling Fluids 

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

C. Production

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

of DOCDs.

D. Oil Characteristics

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

case of DOCDs.

E. New Or Unusual Technology

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

activities in this EP.

F. Bonding

The bond requirement for the activities proposed in this EP 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 

Surety Bonds‖ and National NTL No. 2008-N07, ―Supplemental Bond Procedures.‖

G. Oil Spill Financial Responsibility (OSFR)

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

the wells proposed in the EP according to 30 CFR Parts 250 and 253, and NTL No. 2008-N05, ―Guidelines for 

Oil Spill Financial Responsibility for Covered Facilities.‖

H. Deepwater well control statement

Shell Offshore Inc., BOEM Operator Number 0689, has the financial capability to drill a relief well and conduct 

other emergency well control operations.

I. Suspension of Production

Information regarding Suspension of Production is not included in this EP as such information is only 

necessary in the case of DOCDs.
J. Blowout scenario

Summary

This Section 2j was prepared by Shell Offshore Inc. (Shell) pursuant to the guidance provided in the Bureau 

of Ocean Energy Management, Regulation and Enforcement‘s (BOEM) Notice to Lessees (NTL) No. 2010-N06 

with respect to blowout and worst case discharge scenario descriptions. 

Shell focuses on an integrated, three-pronged approach to a blowout, including prevention, intervention 

/containment, and recovery. Shell believes that the best way to manage blowouts is to prevent them from 

happening. Significant effort goes into the design and execution of wells and into building and maintaining 

staff competence with the goal of safe and environmentally sound well construction. Shell continues to invest 

independently in Research and Development (R&D) to improve safety and reliability of our well systems. Shell 

intends to comply with all applicable laws, regulations, rules and Notice to Lessees.

Shell is investing in R&D to improve containment systems. As outlined in Shell‘s Oil Spill Response Plan 

(OSRP), and detailed in EP Section 9a (ii), Shell has contracts with Oil Spill Removal Organizations (ORSOs) to 

provide the resources necessary to respond to this Worst Case Discharge (WCD) scenario.

The Worst Case Discharge (WCD) blowout scenario for Rydberg Deep is calculated for the MC-525 C location 

of the target Sand and based on the guidelines outlined in NTL No. 2010-N06 along with subsequent 

Frequently Asked Questions (FAQ). Shell is submitting MC-525 C well location as the worst-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 meets or exceeds this WCD. The WCD does not take 

into account potential flow mitigating factors such as well bridging, obstructions in wellbore, reservoir 

barriers, or early intervention. A summary of the WCD rate and spill volume for the total duration to drill a 

relief well is contained in Table 1 below.

Uncontrolled blowout rate (first 30-days average daily rate) 

(Note: this number includes max daily rate of 271,000 bbl/d on 

first day) 233,000 bopd 

Duration of flow (days) based on relief well 157 days

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

Table 1 Worst Case Discharge Summary

The Rydberg Deep prospect is located approximately 79 miles east-southeast of the nearest shoreline in the 

Gulf of Mexico (GOM), in water depths between approximately 7,400‘ and 7,600‘ across the prospect. The 

structural component of the target is defined by a 3-way against faults and salt, with the top of the objective 

near -24,858 ft subsea (SS) at the well C location. The only objective horizon with predicted flow potential is 

the target reservoir.

1) Purpose

Pursuant to 30 CFR 250.213(g), 250.219, 250.250, and NTL No. 2010-N06, this document provides a blowout 

scenario description, further information regarding any potential oil spill, the assumptions and calculations 

used to determine the WCD and the measures taken to 1) 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 regional target formation offset wells data and 

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) Background 

This attachment has been developed to document the additional information requirements for Exploration 

Plans as requested by NTL No. 2010-N06 in response to the explosion and sinking of the Mobile Offshore 

Drilling Unit (MODU) Deepwater Horizon.
3) Information Requirements 

a) Blowout scenario 

All five locations in the proposed Rydberg Deep EP were assessed for WCD. The MC 525 well from 

the proposed C location near the crest of the trap represented the highest flow potential. The C well 

will be drilled to the target reservoir as outlined in the Geological and Geophysical Information 

Section of the Initial EP using a subsea wellhead system, conductor, surface and intermediate casing 

program, and using a MODU rig with a marine riser and subsea blowout preventer (BOP). A 

hydrocarbon influx and a well control event are modeled to occur from the target reservoir. The 

simulated blowout modeled results in unrestricted flow from the well at the seafloor, which 

represents the WCD (no restrictions in wellbore, failure/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-525 

Facility Designation Noble Globetrotter

Distance to Nearest Shoreline (miles) 79 Statute miles

Uncontrolled blowout rate (first 30-days average daily rate) 

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

233,000 bopd

Table 2 Estimated Flow Rates of a Potential Blowout

c) Total volume and maximum duration of the potential blowout

Duration of flow (days) 157 days total duration to drill relief well 

(14 rig mob, 4 transit, 111 spud to top target, 28 ranging). 

Total volume of spill (bbls) 28.14 MMBO based on 157 days flowing. 

Note: From CMG dynamic reservoir model 

Note: (233,000 bopd * 30 days) + (166,500 bopd * 127 days) = ~28.14 

MMBO over 157 days.

Table 3 Estimated Duration and Volume of a Potential Blowout

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

differences between the first 24-hour volume and 30-day average rate. At very short times, e.g. 

during the first 24 hours, the pressure profile in the reservoir changes from the moment when a well 

first starts flowing (transient pressure profile) to a pseudo-steady state pressure profile with time, 

and as a result the rate declines. At somewhat longer time scales, effects such as reservoir voidage 

and the impact of boundaries can cause the rate to drop continuously with production. Simulation 

models can include these effects and form the basis of the NTL No. 2010-N06 calculations for 24-

hour and 30-day rates as well as maximum duration volumes.

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

e) Potential for the well to bridge over 

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

including in-situ stress, rock strength, and fluid velocities at the sand face. Given the substantial fluid 

velocities inherent in the WCD, and the scenario as defined where the formation is not supported by 

a cased and cemented wellbore, it is possible that the borehole may fail/collapse/bridge over within 

the span of a few days, significantly reducing the outflow rates. However, the WCD scenario 

contained in this report does not include any bridging. 
f) Likelihood for intervention to stop the blowout. 

Safety of operations is Shell‘s top priority. Maintaining well control at all times to prevent a blowout is 

the key focus of our operations. This is derived from robust standards, well design, prudent 

operations, competency of personnel, and strong HSE 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 NTL No. 2010-

N05 (to the extent applicable) and the Drilling Safety Rule with respect to Remotely Operated Vehicle 

(ROV) hot stab capabilities, a deadman system, and an autoshear system.

Containment: The experience of gaining control over the Macondo well has resulted in a better 

understanding of the necessary equipment and systems for well containment. As a result, industry 

and government are better equipped and prepared today to contain an oil well blowout in deepwater 

(See page 17 of the Decision Memorandum dated October 1, 2010). Shell is further analyzing these 

advances and incorporating them into its comprehensive approach to help prevent and, if needed, 

control another deepwater control incident. 

Should the interventions at the well not be possible, specialized equipment will be used to connect to 

a riser stub, damaged connector, casing stub, or to the sea floor and allow the well to be shut-in to 

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

be available from the Marine Well Containment Company (MWCC). If full shut-in, following capping is 

not possible because of well integrity issues, the well can be flowed with back-pressure maintained 

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

Containment Company which has the containment equipment and contracts for access to response 

capability. The response capability will incorporate lessons learned and technology advances as they 

apply to containment. The MWCC website can be accessed for a full description of the systems and 

components. The MWCC owns, maintains, and will deploy both existing equipment and equipment 

being constructed for well intervention and containment. The newly constructed system has been 

designed to be flexible and adaptable, and be responsive to a wide range of potential scenarios, 

deepwater depths up to 10,000 feet, weather conditions, and flow rates. The system components will 

be fully tested to ensure functionality and will be maintained in a state of continuous operational

readiness. In the event of a future incident, mobilization to the field will start within days and the 

system will be fully operational within weeks. The new containment system will further enhance 

Shell‘s Regional OSRP. A detailed capping proposal will be provided as part of the Application Permit 

to Drill (APD) submission.

Shell is investing in Research and Development activities on its own to identify additional containment 

components and equipment that will potentially increase the range of applications and effectiveness 

for equipment similar to that of MWCC, and systems that can be deployed more effectively in the 

water column that resemble ―tents or capture domes‖, and thus enhance well shut-in capability. 

g) Availability of a rig to drill a 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, and the Noble Bully 1, will be the 

preferred rigs for blowout intervention work. However, moored rigs can also be used in some 

scenarios. 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 the appropriate rig. Shell‘s current contracted rigs capable 

of operating at Rydberg Deep water depths and reservoir depths are in the following table:
Rig Name Rig Type

Noble Danny Adkins dynamically positioned semi

Noble Bully 1 dynamically positioned drill ship

Deepwater Nautilus Moored semi

Noble Jim Thompson Moored semi

Noble Globetrotter* dynamically positioned drill ship

 Table 4 Shell Contracted Rigs Capable at Rydberg Deep.

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

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

* Noble Globetrotter estimated arrival March 2012

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

Relief well operations will immediately take priority and displace any activity from Shell‘s contracted 

rig fleet. Table 4 lists the Shell contracted rigs capable of operating at Rydberg Deep. It is expected 

to take an average of 14 days to safely secure the well that the rig is working on up to the point the 

rig departs location, and an additional 4 days transit to mobilize to the relief well site depending on 

distance to the site. The relief well will take approximately 111 days to drill down to the last casing 

string above the blowout zone, approximately 28 days for precision ranging activity to intersect the 

blowout well bore. Total time to drill a relief well would be ~157 days for the Rydberg Deep relief 

well.

If a moored rig is chosen to conduct 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. Relief well locations well be planned 

1,500-3,000 ft from the existing well location

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

blowout.

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

below are the measures employed by Shell with the goal of no harm to people or the environment. 

The Macondo incident has highlighted the importance of these practices. The lessons learned from 

the investigation are, and will continue to be, incorporated into our operations. Measures proposed to 

enhance the ability to prevent a blowout and to reduce the likelihood of a blowout include the 

following:

Standards: 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 a 

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 internal 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 Notice to Lessees. Shell works closely with rig contractors to 

ensure proper upkeep of all rig equipment, which meets or exceeds the strictest of Shell, industry, or 

regulatory requirements. Well tangibles are governed by our internal quality assurance/control 

standards and industry standards.

MWD/LWD/PWD Tools: Shell intends to use these tools at Rydberg Deep. The MWD/LWD/PWD 

tools are run on the drill string so that data on subsurface zones can be collected as the well 

advances in real time instead of waiting until the drill string is pulled to run wireline logs. Data from 

the tools are monitored and interpreted real time against prognosis to provide early warning of 

abnormal pressures to allow measures to be taken to progress the well safely. 

Mud Logger: Mud logging personnel continually monitor returning drilling fluids for indications of

hydrocarbons, utilizing both a hot wire and a gas chromatograph. An abrupt increase in gas or oil 

carried in the 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 drilling foreman and Shell representative to report any observed 

anomalies so appropriate action can be taken.

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

support traditional rig-site monitoring since 2003. Well site operations are lived virtually by onshore 

teams consisting of geoscientists, petrophysicists, well engineers, and 24/7 monitoring specialists. 

The same real time well control indicators monitored by the rig personnel are watched by the 

monitoring specialist for an added layer of redundancy. 

Competency and Behavior: A structured training program for Well Engineers and 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, and 

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 

specific requirement of our internal well control standards. The WCCP in turn is part of the wider 

emergency response framework within Shell that addresses the overall organization response to an 

emergency situation. Resources are 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 

mobilization plans for personnel, material and services for well control procedures. The plan 

references individual activity checklists, a roster of equipment and services, initial information 

gathering forms, a generic description of relief well drilling, strategy and guidelines, intervention 

techniques and equipment, site safety management, exclusion zones, and re-boarding. 
k) Arrangements for drilling a relief well 

The size of the Shell contracted rig fleet in the GOM from 2011-2015 ensures that there is adequate 

well equipment (e.g. casing and wellhead) available for relief wells. Rigs and personnel will also be 

readily available within Shell, diverted from their active roles elsewhere. Resources from other 

operators can also be leveraged should the need arise. Generally, relief well plans will mirror the 

blowout well, incorporating any learning on well design based on root cause analysis of the blowout. 

A generic 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 EP as such information is not required by 

BOEM GOMR.
SECTION 3: GEOLOGICAL AND GEOPHYSICAL INFORMATION

A. Geological description

Proprietary data.

B. Structure Contour Map(s)

Proprietary data.

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

Proprietary data.

D. Geological Structure Cross-section(s)

Proprietary data.

E. Shallow Hazards Report

The following reports were used for our analysis:

AUV Hazard study prepared by C&C Technologies, dated February 2009, Project # 083926-084483, for 

Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, and 613, for Mississippi 

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

Previously filed Geohazards Assessment No. 2400-2040 for DeSoto Canyon Blocks 485 and 529 and 

Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and 

Murphy E&P‘s previously submitted shallow hazards report No. 2400-2070, prepared by Fugro Geoservices, 

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

Shallow Hazards Assessment

History

Shell is submitting an Initial Exploration Plan (EP) and AUV Hazard study prepared by C&C Technologies, 

dated February 2009 (Project # 083926-084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 

567, 568, 569, 611, 612, and 613), for Mississippi Canyon 525, Proposed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400-2040 for DeSoto Canyon Blocks 485 and 529 and 

Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and 

Murphy E&P‘s previously submitted shallow hazards report No. 2400-2070, prepared by Fugro Geoservices, 

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

Proposed Location A, Mississippi Canyon 525:

Datum: D_North_American_1927

Projection: Transverse_Mercator

NAD_1927_BLM_Zone_16N

X = 1,331,766 ft; Latitude = 28.460847229°N; Inline= 13,004; 1,206‘ FWL

Y = 10,329,562 ft; Longitude = -87.960895381°W; Crossline =10,166; 1,882‘ FSL
Mississippi Canyon 525, Proposed Location A is located in a water depth of approximately 7,476 feet. There 

is no evidence of seafloor or near-surface faulting within 2,000 feet of Proposed Location A. Proposed 

Location A will be positioned 15,598 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location A consists of Unit 1 approximately 

329 feet of normal marine drape overlying Unit 2 which is 123 feet of interbedded thin sands, silts and clayprone distal slope fan deposits. Unit 3 is identified 452 to 1,910 feet below the mud line, consisting of 

approximately 1,458 feet of muds and fine-grained mass transport deposits. Unit 4 is identified 1,910 to 

2,530 feet below the mud line, consisting of 620 feet of muddy mass-transport complex deposits. Unit 5 is 

identified 2,530 to 4,004 feet below the mud line, consisting of 1,474 feet of sand-prone, channel/overbank 

deposits interbedded with fine-grained mass transport deposits. Unit 6 is identified 4,004 to 7,320 feet below 

the mud line, consisting of 810 feet of fine-grained mass transport deposits with possible interbedded 

discontinuous sands over sand-prone channel/overbank deposits interbedded with fine-grained mass 

transport deposits, over a 2506 foot-thick section consisting of mostly muds interbedded with sand over a 

more mud-prone section. Unit 7 is identified 7,320 to 11,551 feet below the mud line. This 4,231 foot-thick 

unit consists of a potential sand-prone interval near the top, with a more mud-dominated structure in the 

lower part of the interval.

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

approximately 4,425 feet below the mud line. There are no other amplitude anomalies or bright-spots 

identified in the vicinity of Mississippi Canyon 525, Proposed Location A. Proposed Location A is not expected 

to penetrate any amplitude anomalies.

Moderately low potential for shallow gas is identified 4,004 to 7,320 feet below the mud line. Low potential 

for shallow gas is identified from the seafloor to 4,004 feet below the mud line, and 7,320 to 11,551 feet 

below the mud line. 

The potential for shallow water flow is identified as low from the seafloor to 11,551 feet below the mud line 

for Mississippi Canyon, Proposed Location A.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location B, Mississippi Canyon 525:

Datum: D_North_American_1927

Projection: Transverse_Mercator

NAD_1927_BLM_Zone_16N

X = 1,338,030 ft; Latitude = 28.461616320°N; Inline= 13,116; 7,470‘ FWL 

Y = 10,329,792 ft; Longitude = -87.941402002°W; Crossline =10,062; 2,112‘ FSL

Mississippi Canyon 525, Proposed Location B is located in a water depth of approximately 7,566 feet. There 

is no evidence of seafloor or near-surface faulting within 2,000 feet of Proposed Location B. Proposed 

Location B will be positioned 20,468 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location B consists of Unit 1 approximately 

257 feet of normal marine drape overlying Unit 2, which is 101 feet of interbedded thin sands, silts and clayprone distal slope fan deposits. Unit 3 is identified 358 to 1,870 feet below the mud line, consisting of 

approximately 1,512 feet of muds and fine-grained mass transport deposits. Unit 4 is identified 1,870 to 

2,425 feet below the mud line, consisting of 555 feet of fine-grained mass-transport complex deposits. Unit 5 

is identified 2,425 to 3,858 feet below the mud line, consisting of 1,433 feet of sand-prone, channel/overbank 

deposits interbedded with fine-grained mass transport deposits. Unit 6 is identified 3,858 to 7,078 feet below 

the mud line, consisting of 956 feet of fine-grained mass transport deposits with possible interbedded 

discontinuous sands over sand-prone channel/overbank deposits interbedded with fine-grained mass 

transport deposits and a 2,264 foot-thick unit consisting of mostly muds interbedded with sand over a more 

mud-prone section. Unit 7 is identified 7,078 to 10,885 feet below the mud line. This 3,807 foot-thick unit 

consists of a potential sand-prone interval near the top, with a more mud-dominated structure in the lower 

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

approximately 4,234 feet below the mud line. There are no other amplitude anomalies or bright-spots 

identified in the vicinity of Mississippi Canyon 525, Proposed Location B. Proposed Location B is not expected 

to penetrate any amplitude anomalies. 

Low potential for shallow gas is identified the seafloor 10,885 feet below the mud line. 

The potential for shallow water flow is identified as low from the seafloor to 10,885 feet below the mud line 

for Mississippi Canyon, Proposed Location B.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location C, Mississippi Canyon 525:

Datum: D_North_American_1927

Projection: Transverse_Mercator

NAD_1927_BLM_Zone_16N

X = 1,333,970 ft; Latitude = 28.461214644°N; Inline= 13,044; 3,410‘ FWL 

Y = 10,329,678 ft; Longitude = -87.954037508°W; Crossline =10,130; 1,998‘ FSL

Mississippi Canyon 525, Proposed Location C is located in a water depth of approximately 7,505 feet. There 

is no evidence of seafloor or sub-surface faulting within 2000 feet of Proposed Location C. Proposed Location 

C will be positioned 17,232 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location C consists of Unit 1 approximately 

300 feet of normal marine drape overlying Unit 2, which is 117 feet of interbedded thin sands, silts and clayprone distal slope fan deposits. Unit 3 is identified 417 to 1,894 feet below the mud line, consisting of 

approximately 1,477 feet of muds and fine-grained mass transport deposits. Unit 4 is identified 1,894 to 

2,482 feet below the mud line, consisting of 588 feet of fine-grained mass-transport complex deposits. Unit 5 

is identified 2,482 to 3,966 feet below the mud line, consisting of 1,484 feet of sand-prone, channel/overbank 

deposits interbedded with fine-grained mass transport deposits. Unit 6 is identified 3,966 to 7,215 feet below 

the mud line, consisting of 812 feet of fine-grained mass transport deposits with possible interbedded 

discontinuous sands over sand-prone channel/overbank deposits interbedded with fine-grained mass 

transport deposits, and a 2,437 foot-thick section consisting of mostly muds interbedded with sand over a 

more mud-prone section. Unit 7 is identified 7,215 to 11,275 feet below the mud line. This 4,060 foot-thick 

unit consists of a potential sand-prone interval near the top, with a more mud-dominated structure in the 

lower part of the interval.

A moderate amplitude anomaly is identified approximately 4,400 feet below the mud line in Unit 6. Another 

moderate amplitude anomaly is identified approximately 475 feet from Proposed Location C within Unit 

5.approximately 3,200 feet below the mud line. There are no other amplitudes or bright-spots identified in 

the vicinity of Mississippi Canyon 525, Proposed Location C. The casing program for Proposed Location C is 

designed for possible amplitude penetration.

Moderately low potential for shallow gas is identified 2,482 to 3,966 feet below the mud line. Low potential 

for shallow gas is identified from the seafloor to 2,482 feet below the mud line, and 3,966 to 11,275 feet 

below the mud line. 

The potential for shallow water flow is identified as low from the seafloor to 11,275 feet below the mud line 

for Mississippi Canyon, Proposed Location C.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Datum: D_North_American_1927

Projection: Transverse_Mercator

NAD_1927_BLM_Zone_16N

X = 1,336,174 ft; Latitude = 28.467325943°N; Inline= 13,120; 5,614‘ FWL 

Y = 10,331,882 ft; Longitude = -87.947230796°W; Crossline =10,130; 4,202‘ FSL

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

is no evidence of seafloor or near-surface faulting within 2,000 feet of Proposed Location D. Proposed 

Location D will be positioned 20,347 feet northeast of Shell‘s previously drilled wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location D consists of Unit 1 approximately 

271 feet of normal marine drape overlying Unit 2, which is 117 feet of interbedded thin sands, silts and clayprone distal slope fan deposits. Unit 3 is identified 388 to 1,891 feet below the mud line, consisting of 

approximately 1,503 feet of muds and fine-grained mass transport deposits. Unit 4 is identified 1,891 to 

2,407 feet below the mud line, consisting of 516 feet of fine-grained mass-transport complex deposits. Unit 5 

is identified 2,407 to 3,861 feet below the mud line, consisting of 1,454 feet of sand-prone, channel/overbank 

deposits interbedded with fine-grained mass transport deposits. Unit 6 is identified 3,861 to 7,141 feet below 

the mud line, consisting of 908 feet of fine-grained mass transport deposits with possible interbedded 

discontinuous sands over sand-prone channel/overbank deposits interbedded with fine-grained mass 

transport deposits and a 2,372 foot-thick section consisting of mostly muds interbedded with sand over a 

more mud-prone section. Unit 7 is identified 7,141 to 11,038 feet below the mud line. This 3,897 foot-thick 

unit consists of a potential sand-prone interval near the top, with a more mud-dominated structure in the 

lower part of the interval.

Proposed Location D may penetrate a moderately high amplitude anomaly in Unit 6, approximately 4,275 feet 

below the mud line. There are no other amplitudes or bright-spots identified in the vicinity of Mississippi 

Canyon 525, Proposed Location D. The casing program for Proposed Location D is designed for possible 

amplitude penetration.

Moderately high potential for shallow gas is identified 3,861 to 7,141 feet below the mud line, in Unit 6. Low 

potential for shallow gas is identified from the seafloor to 3861 feet below the mud line and 7,141 to 11,038 

feet below the mud line. 

The potential for shallow water flow is identified as low from the seafloor to 11,038 feet below the mud line 

for Mississippi Canyon, Proposed Location D.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location E, Mississippi Canyon 525

Datum: D_North_American_1927

Projection: Transverse_Mercator

NAD_1927_BLM_Zone_16N

X = 1,331,418 ft; Latitude = 28.468817633°N; Inline= 13,048; 858‘ FWL

Y = 10,332,462 ft; Longitude = -87.962050905°W; Crossline =10,222; 4,782‘ FSL

Mississippi Canyon 525, Proposed Location E is located in a water depth of approximately 7,466 feet. There 

is no evidence of seafloor or sub-surface faulting within 2,000 feet of Proposed Location E. Proposed 

Location E will be positioned 17,653 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location E consists of Unit 1 approximately 

300 feet of normal marine drape overlying Unit 2, which is 126 feet of interbedded thin sands, silts and clayprone distal slope fan deposits. Unit 3 is identified 426 to 1,884 feet below the mud line, consisting of 

approximately 1,458 feet of muds and fine-grained mass transport deposits. Unit 4 is identified 1,884 to 

2,496 feet below the mud line, consisting of 612 feet of fine-grained mass-transport complex deposits. Unit 5 

is identified 3,943 to 7,320 feet below the mud line, consisting of 1,447 feet of sand-prone, channel/overbank 

deposits interbedded with fine-grained mass transport deposits. Unit 6 is identified 3,943 to 7,320 feet below 

the mud line, consisting of 872 feet of fine-grained mass transport deposits with possible interbedded 
discontinuous sands over sand-prone channel/overbank deposits interbedded with fine-grained mass 

transport deposits, and a 2505 foot-thick section consisting of mostly muds interbedded with sand over a 

more mud-prone section. Unit 7 is identified 7,320 to 11,540 feet below the mud line. This 4,220 foot-thick 

unit consists of a potential sand-prone interval near the top, with a more mud-dominated structure in the 

lower part of the interval.

There are no amplitude anomalies identified in the vicinity of Proposed Location E. Proposed Location E is 

not expected to penetrate any amplitude anomalies.

Low potential for shallow gas is identified from the seafloor to 11,540 feet below the mud line for Mississippi 

Canyon, Proposed Location E. 

The potential for shallow water flow is identified as low from the seafloor to 11,540 feet below the mud line. 

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Adam Chow Arlette. C. Nunez

Geophysicist Shallow Hazard Coordinator

F. High-Resolution Seismic Lines

Proprietary data.

G. Tophole Prognosis

Proprietary data. (ESR maps can be found in Section 6, Attachment 6A.)

H. Stratigraphic Column with Time vs depth table

Proprietary data.

I. Geochemical Information

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

J. Future G&G Activities

This information is not required for Plans submitted in the GOM Region.
SECTION 4: HYDROGEN SULFIDE (H2S) INFORMATION

A. Concentration 

0-40 ppm

B. Classification

Based on 30 CFR 250.490(c), Shell requests that the Regional Supervisor, Field Operations, determine the zones in the 

proposed drilling operations in this plan to be classified as an area where the absence of H2S is unknown.

Shell will submit to the appropriate BOEM GOMR district office an H2S Contingency Plan prepared according to 30 CFR

250.490(f) before conducting the proposed exploration activities.

C. Modeling Report

We do not anticipate to encounter or handle H2S at concentrations greater than 500 parts per million (ppm) and therefore 

have not included modeling for H2S.
SECTION 5: MINERAL RESOURCE CONSERVATION INFORMATION

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

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

A. Chemosynthetic Communities Report

Biological Information

In accordance with NTL 2009-G40, dated January 27, 2010, for water depths greater than 984 feet:

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

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

within 2,000 feet of each proposed mud and cuttings discharge location.

History

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

February 2009, Project # 083926-084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 

568, 569, 611, 612, and 613, for Mississippi Canyon 525, Proposed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400-2040 for DeSoto Canyon Blocks 485 and 529 and 

Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and 

Murphy E&P‘s previously submitted shallow hazards report No. 2400-2070, prepared by Fugro Geoservices, 

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

Proposed Location A, Mississippi Canyon 525:

X = 1,331,766 1206‘ FWL

Y = 10,329,562 1882‘ FSL

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

no evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features within 2000‘ 

of Proposed Location A. Proposed Location A will not disturb any high-density areas of chemosynthetic 

communities.

Proposed Location A will be positioned 15598 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. 

Proposed Location A will not disturb any previously drilled wellsites.

Sonar Target #24 is located 2860 feet southeast of Proposed Location A. This target has been identified as 

modern debris. An avoidance zone of 100‘ surrounds this target. There are no other sonar targets identified 

within 3000‘ of Proposed Location A.

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

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location B, Mississippi Canyon 525:

X = 1,338,030 7470‘ FWL

Y = 10,329,792 2112‘ FSL

Mississippi Canyon 525, Proposed Location B is located in a water depth of approximately 7,566 feet. There 

is no evidence of seafloor or near-surface faulting, slumping, amplitude or fluid expulsion features within 

2000‘ of Proposed Location B. Proposed Location B will not disturb any high-density areas of chemosynthetic 

communities.

Proposed Location B will be positioned 20,468 feet northeast of Shell‘s previously drilled MC568 #1 wellsite. 

Proposed Location B will not interfere with any previously drilled wellsites.
Sonar Target #20 is located 909 feet north of Proposed Location B. Sonar Target #19 is located 1891 feet 

east of Proposed Location B. Sonar Target #19 is located 1891 feet north of Proposed Location B. All of 

these targets are identified as modern debris. Avoidance zones of 100‘ surround each target. There are no 

other sonar targets identified within 3,000‘ of Proposed Location B.

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

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location C, Mississippi Canyon 525:

X = 1,333,970 3410‘ FWL

Y = 10,329,678 1998‘ FSL

Mississippi Canyon 525, Proposed Location C is located in a water depth of approximately 7505 feet. There is 

no evidence of seafloor or near-surface faulting, slumping, amplitude or fluid expulsion features within 2000‘ 

of Proposed Location C. Proposed Location C will not disturb any high-density areas of chemosynthetic 

communities.

Proposed Location C will be positioned 17232 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. 

Proposed Location C will not interfere with any previously drilled wellsites.

There are no sonar targets identified within 3,000‘ of Proposed Location C.

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

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Proposed Location D, Mississippi Canyon 525:

X = 1,336,174 5,614‘ FWL

Y = 10,331,882 4,202‘ FSL

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

is no evidence of seafloor or near-surface faulting, slumping, amplitude or fluid expulsion features within 

2,000‘ of Proposed Location D. Proposed Location D will not disturb any high-density areas of 

chemosynthetic communities.

Proposed Location D will be positioned 20,347 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. 

Proposed Location D will not interfere with any previously drilled wellsites.

Sonar Target #16 is located 983 feet north of Proposed Location D. Sonar Target #18 is located 1,382 feet 

east of Proposed Location D. Sonar Target #20 is located 2064 feet southeast of Proposed Location D. All of 

these targets are identified as modern debris. Avoidance zones of 100‘ surround each target. There are no 

other sonar targets identified within 3,000‘ of Proposed Location D.

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

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

X = 1,331,418 858‘ FWL

Y = 10,332,462 4782‘ FSL

Mississippi Canyon 525, Proposed Location E is located in a water depth of approximately 7,466 feet. There 

is no evidence of seafloor or near-surface faulting, slumping, amplitude or fluid expulsion features within 

2,000‘ of Proposed Location E. Proposed Location E will not disturb any high-density areas of chemosynthetic 

communities.

Proposed Location E will be positioned 17,653 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. 

Proposed Location E will not interfere with any previously drilled wellsites.

There are no sonar targets identified within 3,000‘ of Proposed Location E.

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

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3-D seismic, Enhanced 

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

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

Adam Chow Arlette. C. Nunez

Geophysicist Shallow Hazard Coordinator

B - F

Pursuant to NTL No. 2008-G04 the proposed operations covered by this EP do not involve operations 

impacting the following: Topographic features map, Topographic features statement (shunting), Live 

bottoms, (Pinnacle Trend) map, Live bottoms (low relief) map, or potentially sensitive biological features 

map.

G. Remotely Operated Vehicle (ROV) Monitoring Plan

In accordance with the provisions of NTL 2008-G06, Remotely Operated Vehicle Surveys in Deepwater, 

Mississippi Canyon 525 is located in Grid 17. Grid 17 is an area that does not have adequate ROV survey 

coverage; therefore the pre- and post-ROV survey will be run in accordance with the NTL. 

Survey No. 1 will be conducted using the Rig based ROV equipped with video imaging capabilities prior to 

commencing operations on the well. The survey pattern will consist of six transects centered on the existing 

well with tracks extending 100 meters away from the well on bearings of 30°, 90°, 150°, 210°, 270°, and 

330°. The seafloor will be videotaped continuously along each track and close-up footage recorded of any 

animals or features. An identical survey will be conducted following drilling operations but prior to moving 

the rig off location. During both surveys, all biological and physical observations will be documented using 

Form MMS-141. Complete documentation, including videotapes, of both surveys will be submitted to the 

GOMR within 60 days of the final survey.

H. Threatened and Endangered Species Information

There are 5 species of sea turtles that may be found in the Gulf of Mexico (see table below). No critical 

habitat for these species has been designated in the Gulf of Mexico.

Common Name Scientific Name T/E Status

Hawksbill Turtle Eretmochelys imbricata E

Green Turtle Chelonia mydas T

Kemp's Ridley Turtle Lepidochelys kempii E

Leatherback Turtle Dermochelys coriacea E

Loggerhead Turtle Caretta caretta T
There are 29 species of marine mammals that may be found in the Gulf of Mexico (see table below). Of the 

species listed as Endangered, only the Sperm whale is commonly found in the project area. No critical 

habitat for these species has been designated in the Gulf of Mexico.

Common Name Scientific Name T/E Status

Atlantic Spotted Dolphin Stenella frontalis

Blainville's Beaked Whale Mesoplodon densirostris

Blue Whale Balaenoptera musculus E

Bottlenose Dolphin Tursiops truncatus

Bryde's Whale Balaenoptera edeni

Clymene Dolphin Stenella clymene

Cuvier's Beaked Whale Ziphius cavirostris

Dwarf Sperm Whale Kogia simus

False Killer Whale Pseudorca crassidens

Fin Whale Balaenoptera physalus E

Fraser's Dolphin Lagenodelphis hosei

Gervais' Beaked Whale Mesoplodon europaeus

Humpback Whale Megaptera novaeangliae E

Killer Whale Orcinus orca

Melon-headed Whale Peponocephala electra

Minke Whale Balaenoptera acutorostrata

Northern Right Whale Eubalaena glacialis E

Pantropical Spotted Dolphin Stenella attenuata

Pygmy Killer Whale Feresa attenuata

Pygmy Sperm Whale Kogia breviceps

Risso's Dolphin Grampus griseus

Rough-toothed Dolphin Steno bredanensis

Sei Whale Balaenoptera borealis E

Short-finned Pilot Whale Globicephala macrorhynchus

Sowerby's Beaked Whale Mesoplodon bidens

Sperm Whale Physeter macrocephalus E

Spinner Dolphin (Long-snouted) Stenella longirostris

Striped Dolphin Stenella coeruleoalba

West Indian manatee Trichechus manatus E

Section 18 of this plan discusses potential impacts and mitigation measures related to threatened and 

endangered species. 

I. Archaeological Report

Report Information

An archaeological report was generated by C&C Technologies for the area. The report is AUV Hazard Study, 

Blocks 479, 780, 481, 523, 524, 525, 567, 568, 569, 611, 612 & 613, Mississippi Canyon Area, Project 

#083926-08483, February 2009.

Archaeological Statement

One hundred thirty-seven (137) unidentified sonar contacts, including two debris zones, were recorded in the 

survey area. These sonar contacts are relatively small and could be debris related to modern shipping 

activities in the area. Anchor and anchor mooring for any proposed well drilling should avoid the locations of 

any existing pipelines and sonar contacts due to potential entanglement.

Shell will comply with all conditions of NTL 2005-G07.
J. Air and Water Quality Information

Pursuant to NTL 2008-G04 the proposed operations covered by this EP do not require Shell to provide 

additional information relating to air and water quality information. For specific information relating to air 

and water quality information please refer to the EIA, Attachment 18. 

K. Socioeconomic Information

Pursuant to NTL 2008-G04 the proposed operations covered by this EP do not require Shell to provide 

additional information relating to air and water quality information. For specific information relating to 

socioeconomic information please refer to Section 18 of this Plan. 
SECTION 7: WASTE AND DISCHARGE INFORMATION

A. Discharge to GOM or Downhole

Note: Please specify if the amount reported is a total or per well amount Rydberg Deep

Type of Waste and Composition Composition Projected Amount Discharge rate Discharge Method Answer yes or no

Will drilling occur ? If yes, you should list muds and cuttings

EXAMPLE: Cuttings wetted with ynthetic based fluid 

Cuttings generated while using synthetic 

based drilling fluid. X bbl/well X bbl/day discharge pipe No

Water-based drilling fluid barite, additives, mud 25,000 bbls / well 1,700 bbls / day

Overboard and seafloor discharge prior to 

marine riser installation No

Water-based drilling fluid barite, additives, mud 1,000 bbls / well 1,000 bbls / day discharge overboard No

Cuttings wetted with water-based fluid

cuttings coated with water based drilling 

mud 3,500 bbls / well 233 bbls / day Sea bed during riserless drilling No

Cuttings wetted with synthetic-based fluid 

Cuttings generated while using synthetic 

based drilling fluid. 5,000 bbls / well 40 bbls / day

Overboard discharge line below the water 

level No

Synthetic based drilling fluid adhering to washed drill 

cuttings

Synthetic based drilling fluid adhering to 

washed drill cuttings 150 bbls / well 1 bbl / day

Overboard discharge line below the water 

level No

Chemical product waste 50 bbls / well .5 bbls / day

Treated to meet NPDES limits and 

discharged overboard No

Will humans be there? If yes, expect conventional waste

EXAMPLE: Sanitary waste water X liter/person/day NA chlorinate and discharge No

Domestic waste (kitchen water, shower water) grey water 26,000 bbls/well 203 bbls / day

Grinded to less than 25 mm mesh size and 

discharge overboard No

Sanitary waste (toilet water) treated sanitary waste 6,000 bbls/well 30 bbls / day

Treated in the MSD** prior to discharge to 

meet NPDES limits No

Is there a deck? If yes, there will be Deck Drainage

Deck Drainage Wash and rainwater 3,900 bbls / well 20 bbls / day Drained overboard through deck scuppers No

Will you conduct well treatment, completion, or workover? 

well treatment fluids NA NA NA NA No

well completion fluids NA NA NA NA No

workover fluids NA NA NA NA No

Miscellaneous discharges. If yes, only fill in those associated with your activity. 

Desalinization unit discharge Rejected water from watermaker unit 74,100 bbls / well 380 bbls /day Discharged overboard below waterline No

Blowout prevent fluid Water based 400 bbls/well 50 bbls/day Disharge at seafloor No

Ballast water Uncontaminated seawater 390,000 bbls / well 2,000 bbls / day Discharged overboard Just above waterline No

Bilge water

Bilge and drainage water will be treated to 

MARPOL standards (< 15ppm oil in water). 390,000 bbls / well 2,000 bbls / day

Bilge and drainage water will be treated to 

MARPOL standards (< 15ppm oil in water). No

Excess cement at seafloor Cement slurry

246 bbls/well (assume planned 

100% excess is discharged) 246 bbls / well

Discharged at the seafloor during riserless 

drilling No

Fire water Treated seawater 11,000 bbls / well 2,000 bbls / month Drained overboard through deck scuppers No

Cooling water Treated seawater 23,295,000 bbls / well 145,000 bbls / day

Discharged overboard 40 feet below 

waterline No

Will you produce hydrocarbons? If yes fill in for produced water.

Produced water NA NA NA NA NA

Will you be covered by an individual or general NPDES permit ? GENERAL PERMIT GMG290103

NOTE: If you will not have a type of waste, enter NA in the row. 

TABLE 7A: WASTES YOU WILL GENERATE, TREAT AND DOWNHOLE DISPOSE OR DISCHARGE TO 

THE GOM

Projected 

Downhole 

Projected generated waste Projected ocean discharges Disposal
B. Land, inject, incinerator or recycle table

Rydberg Deep

Solid and Liquid Wastes 

transportation 

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

Will drilling occur ? If yes, fill in the muds and cuttings.

EXAMPLE: Oil-based drilling fluid or mud NA NA NA NA NA

Oil-based drilling fluid or mud NA NA NA NA NA

Synthetic-based drilling fluid or mud used SBF and additives Drums on barges

Newpark Environmental Services 

(Fourchon, La.) or US Liquids of 

Louisiana (Fourchon, La.) 2,500 bbls/well Recycled

Cuttings wetted with Water-based fluid NA NA NA NA NA

Cuttings wetted with Synthetic-based fluid 

Drill cuttings from synthetic 

based interval. storage tank on supply boat.

Newpark Environmental Services 

(Fourchon, La.) or US Liquids of 

Louisiana (Fourchon, La.) 300 bbls / well Recycled

Cuttings wetted with oil-based fluids NA NA NA NA NA

Will you produce hydrocarbons? If yes fill in for produced sand.

Produced sand NA NA NA NA NA

EXAMPLE: trash and debris cardboard, aluminum, barged in a storage bin shorebase z tons total recycle

Trash and debris - recyclables trash and debris storage bins on supply boat

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA 60 lbs/month recylce

Non-Hazardous trash and debris - nonrecyclables trash and debris storage bins on supply boatRepublic/BFI landfill, Sorrento, LA or 

the parish landfill, Avondale, LA. 118 lbs/month landfill

Hazardous waste

paints, solvents and unused 

chemicals drums on supply boat Safety Kleen, Denton, TX 60 lbs/month recylce

Used oil & glycole

used oil, oily rags and pads, 

empty drums and cooking 

oil drums on supply boat

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA 20 bbls/month recycle

Universal waste items

Batteries, lamps, glass and 

mercury-contaminated 

waste drums on supply boat Lamp Environmental, Hammond, LA 30 bbls/month landfill

NOTE: If you will not have a type of waste, enter NA in the row. 

Waste Disposal

TABLE 7B: WASTES YOU WILL TRANSPORT AND /OR DISPOSE OF ONSHORE 

Will you have additional wastes that are not permitted for discharge? If 

yes, fill in the appropriate rows. 

Note: Please specify whether the amount reported is a total or per well

Projected generated waste

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 = 3400D2/3 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 H2S 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 

Emission1 

Amounts 

(tons)

Calculated 

Exemption2

Amounts 

(tons)

Calculated

Complex Total 

Emission 

Amounts3

(tons)

PM

SOx

NOx

VOC

CO

1

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

worksheets.

2

List the exemption amounts for your proposed activities calculated by using the formulas in 30 CFR 

250.303(d).

3

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

worksheets

(2) Contact: Tracy Albert, 504.728.4652, tracy.albert@shell.com

(1) Worksheets

Worksheets are included in this plan.
Fuel Usage Conversion Factors Natural Gas Turbines Natural Gas Engines Diesel Recip. Engine REF. DATE

SCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483 AP42 3.2-1 4/76 & 8/84

Equipment/Emission Factors units PM SOx NOx VOC CO REF. DATE

NG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83 AP42 3.2-1& 3.1-1 10/96

NG 2-cycle lean gms/hp-hr 0.00185 10.9 0.43 1.5 AP42 3.2-1 10/96

NG 4-cycle lean gms/hp-hr 0.00185 11.8 0.72 1.6 AP42 3.2-1 10/96

NG 4-cycle rich gms/hp-hr 0.00185 10 0.14 8.6 AP42 3.2-1 10/96

Diesel Recip. < 600 hp. gms/hp-hr 1 0.1835 14 1.12 3.03 AP42 3.3-1 10/96

Diesel Recip. > 600 hp. gms/hp-hr 0.32 0.1835 11 0.33 2.4 AP42 3.4-1 10/96

Diesel Boiler lbs/bbl 0.084 0.3025 0.84 0.008 0.21 AP42 1.3-12,14 9/98

NG Heaters/Boilers/Burners lbs/mmscf 7.6 0.593 100 5.5 84 AP42 1.4-1, 14-2, & 14-3 7/98

NG Flares lbs/mmscf 0.593 71.4 60.3 388.5 AP42 11.5-1 9/91

Liquid Flaring lbs/bbl 0.42 6.83 2 0.01 0.21 AP42 1.3-1 & 1.3-3 9/98

Tank Vapors lbs/bbl 0.03 E&P Forum 1/93

Fugitives lbs/hr/comp. 0.0005 API Study 12/93

Glycol Dehydrator Vent lbs/mmscf 6.6 La. DEQ 1991

Gas Venting lbs/scf 0.0034

Sulfur Content Source Value Units

Fuel Gas 3.33 ppm

Diesel Fuel 0.05 % weight

Produced Gas( Flares) 3.33 ppm

Produced Oil (Liquid Flaring) 1 % weight

Diesel S spec per contract procurement, per Ron Keiser, Domestic Fuels Manager, Shell 

Marine Products (US) Company
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

Shell Offshore Inc Mississippi Canyon 525 OCS-G 31507 NA A-E Sylvia bellone 504.728.7215

OPERATIONS EQUIPMENT RATING MAX. FUEL ACT. FUEL RUN TIME MAXIMUM POUNDS PER HOUR ESTIMATED TONS

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CO

DRILLING 20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

Globetrotter or similar 20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

DP drillship 20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

20-710-GC Prime Mover 6786 327.7638 7866.33 24 148 4.78 2.74 164.42 4.93 35.87 8.49 4.87 292.01 8.76 63.71

8-710-GC Emerg Gen 1298 62.6934 1504.64 1 148 0.91 0.52 31.45 0.94 6.86 0.07 0.04 2.33 0.07 0.51

Diesel Boiler 61 24 148 0.21 0.77 2.14 0.02 0.53 0.38 1.37 3.79 0.04 0.95

Incinerator 1091 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

VESSELS>600hp diesel(crew) 825 39.8475 956.34 24 148 0.58 0.33 19.99 0.60 4.36 1.03 0.59 35.50 1.07 7.75

VESSELS>600hp diesel(supply) 3250 156.975 3767.40 24 148 2.29 1.31 78.74 2.36 17.18 4.07 2.33 139.85 4.20 30.51

Drilling

Platform Rig

(all rig power comes from Platform power)

NO ACTIVITY

PIPELINE

INSTALLATION

NO ACTIVITY

FACILITY

INSTALLATION

NO ACTIVITY

PRODUCTION

NO ACTIVITY

2012 YEAR TOTAL 42.27 24.88 1447.67 43.39 315.92 73.51 43.30 2517.53 75.45 549.40

EXEMPTION CALCULATION DISTANCE FROM LAND IN MILES 2630.70 2630.70 2630.70 2630.70 62598.46

79.0
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

Shell Offshore Inc Mississippi Canyon 525 OCS-G 31507 NA A-E Sylvia bellone 504.728.7215 #REF!

OPERATIONS EQUIPMENT RATING MAX. FUEL ACT. FUEL RUN TIME MAXIMUM POUNDS PER HOUR ESTIMATED TONS

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CO

DRILLING 20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

Globetrotter or similar 20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

DP drillship 20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

20-710-GC Prime Mover 6786 327.7638 7866.33 24 128 4.78 2.74 164.42 4.93 35.87 7.35 4.21 252.55 7.58 55.10

8-710-GC Emerg Gen 1298 62.6934 1504.64 1 128 0.91 0.52 31.45 0.94 6.86 0.06 0.03 2.01 0.06 0.44

Diesel Boiler 61 24 128 0.21 0.77 2.14 0.02 0.53 0.33 1.18 3.28 0.03 0.82

Incinerator 0 0 0.00 0 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

VESSELS>600hp diesel(crew) 825 39.8475 956.34 24 128 0.58 0.33 19.99 0.60 4.36 0.89 0.51 30.70 0.92 6.70

VESSELS>600hp diesel(supply) 3250 156.975 3767.40 24 128 2.29 1.31 78.74 2.36 17.18 3.52 2.02 120.95 3.63 26.39

Drilling

Platform Rig

(all rig power comes from Platform power)

NO ACTIVITY

PIPELINE

INSTALLATION

NO ACTIVITY

FACILITY

INSTALLATION

NO ACTIVITY

PRODUCTION

NO ACTIVITY

2013-2016 YEAR TOTAL 42.27 24.88 1447.67 43.39 315.92 63.57 37.45 2177.32 65.25 475.16

EXEMPTION CALCULATION DISTANCE FROM LAND IN MILES 2630.70 2630.70 2630.70 2630.70 62598.46

79.0
COMPANY AREA BLOCK LEASE PLATFORM WELL

Shell Offshore Inc Mississippi Canyon 525 OCS-G 31507 A-E

Emitted Substance

Year TPY

PM SOx NOx VOC CO

2012 73.51 43.30 2517.53 75.45 549.40

2013 63.57 37.45 2177.32 65.25 475.16

2014 63.57 37.45 2177.32 65.25 475.16

2015 63.57 37.45 2177.32 65.25 475.16

2016 63.57 37.45 2177.32 65.25 475.16

Allowable 2630.70 2630.70 2630.70 2630.70 62598.46
SECTION 9: OIL SPILLS INFORMATION

A. Oil Spill Response Planning

All the proposed activities and facilities in this EP will be covered by the Regional OSRP filed by Shell 

Offshore Inc (0689) in accordance with 30 CFR 250. An update to the Regional OSRP was filed with the 

BOEM October 26, 2010, March 15, 2011, May 31, 2011, July 6, 2011 and August 1, 2011 is pending 

approval. An updated OSRP Certification in accordance with 30 CFR 254.2 was accepted by the BOEM

on August 4, 2011.

Spill Response Sites:

Primary Response Equipment Locations Preplanned Staging Location(s) 

Venice, LA; Houma, LA; Pascagoula, MS; 

Fort Jackson, LA

Fourchon, LA; Pascagoula, MS; Fort Jackson, 

LA; Venice, LA

The names of the oil spill removal organizations (OSRO‘s) under contract include Clean Gulf Associates 

(CGA), Marine Spill Response Company (MSRC), Clean Caribbean America (CCA), and OSRL/EARL.

Worst Case Scenario Determination:

Category Regional OSRP EP

Type of Activity1 Drilling Rig Drilling Rig 

Facility Location (area/block) MC 807 MC 525

Facility Designation2Subsea well A◊ Subsea well C

Distance to Nearest Shoreline (miles) 53 79

Volume3

Storage tanks (total)

Flowlines (on facility)

Pipelines

Uncontrolled blowout (volume per day)

Total Volume

N/A

N/A

N/A

465,000* BOPD

465,000 Bbls

N/A

N/A

N/A

271,000** BOPD

271,000 Bbls

Type of Oil(s) - (crude oil, condensate, 

diesel)

Crude oil Crude oil

API Gravity(s)426o 39o

 *24 hour rate (365,000 BOPD 30 day average)

**24 hour rate (92,000 BOPD 30 day average)

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

covered for 2010-N06 in Plan S-7499 (approved November 22, 2011).

Footnotes:

1. Types of activities include pipeline, platform, caisson, subsea completion or manifold, and mobile drilling rig.

2. E.g., Well No. 2, Platform JA, Pipeline Segment No. 6373.

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

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

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

254.47 (a) and/or (b), as appropriate.

4. Provide API gravity of all oils given under ―Type of Oil(s)‖ above. Estimate for EP‘s.

Since Shell Offshore Inc. has the capability to respond to the appropriate worst-case spill scenario included in 

its regional OSRP, filed with the BOEM October 26, 2010, March 15, 2011, May 31, 2011, July 6, 2011 and 

August 1, 2011 and is pending approval, 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 Offshore Inc. has 

the capability to respond, to the maximum extent practicable, to a worst-case discharge, or a substantial threat 

of such a discharge, resulting from the activities proposed in our EP.
B. Oil Spill Response Discussion

1. Volume of the Worst Case Discharge

Please refer to Section 2j of this EP

2. Trajectory Analysis

Trajectories of a spill and the probability of it impacting a land segment have been projected 

utilizing information in the BOEM Oil Spill Risk Analysis Model (OSRAM) for the Central and Western 

Gulf of Mexico available on the BOEM website using 30 day impact. Offshore areas along the 

trajectory between the source and land segment contact could be impacted. The land segment 

contact probabilities are shown in Table 9.B.1.

Area/Block OCS-G

Launch

Area Land Segment Contact %

Exploratory

MC525 31507 57

Matagorda, TX -

Galveston, TX -

Jefferson, TX -

Cameron, LA 1

Vermilion, LA 1

Iberia, LA -

Terreboone, LA 2

Lafourche, LA 2

Jefferson, LA -

Plaquemines, LA 21

St. Benard, LA 3

Hancok & Harrison, MS 1

Jackson, MS 1

Mobile, AL 1

Baldwin, AL 1

Escambia, FL 1

Okaloosa, FL 1

Walton, FL 1

Bay. FL 1

Franklin, FL -

Table 9.B.1 Probability of Land Segment Impact

C. Resource Identification

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

the BOEM Oil Spill Risk Analysis Model (OSRAM). The environmental sensitivities are identified using 

the appropriate National Oceanic and Atmospheric Administration (NOAA) Environmental 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 525 WCD scenario.
Onshore/Nearshore: Plaquemines Parish has been identified as the most probable impacted 

Parish within the Gulf of Mexico for the Greater than 10 Mile Worst Case Discharge and the 

Exploratory Worst Case Discharge. The Plaquemines Parish has a total area of 2,429 square miles of 

which, 845 square miles of it is land and 1,584 square miles is water. The Plaquemines Parish 

includes two National Wildlife Refuges: Breton National Wildlife Refuge and Delta National Wildlife 

Refuge. This area is also a nesting ground for the brown pelican, an endangered species. Examples 

of Environmental Sensitivity maps for Plaquemines Parish are detailed in the following pages. Key 

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

Offshore: An offshore spill may require an Essential Fishing Habitat (EFH) Assessment. This 

assessment would include a description of the spill, analysis of the potential adverse effects on EFH 

and the managed species; conclusions regarding the effects on the EFH; and proposed mitigation, if 

applicable. 

Significant pre-planning of joint response efforts was undertaken in response to provisions of the 

National Contingency Plan (NCP). Area Contingency Plans (ACPs) were developed to provide a well 

coordinated 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 525 Worst Case Discharge as effectively as 

possible. Applied Science Associates (ASA) conducted a deepwater blowout simulation for The 

Response Group to better determine subsurface and surface evaporation and dispersion rates. 

Below is a table outlining the applicable evaporation and dispersion quantities.

Mississippi Canyon 525

Calculations

(BBLS)

i. 30 Day Average WCD = 233,000 bbls

ii. Subsurface dispersion – 25% (Water Depth = ~7,505 ft) -58,250 bbls

iii. REMAINING WCD AFTER SUBSURFACE DISPERSION 174,750 bbls

iv. Surface dispersion and evaporation – 25% -43,687 bbls

TOTAL REMAINING ~51,800 bbls

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

Shell has contracted OSROs to provide equipment, personnel, materials and support vessels as well 

as temporary storage equipment to be considered in order to cope with a WCD spill. Under adverse 

weather conditions, major response vessels and Transrec 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 Equipment

Upon notification of the spill, Shell would request a partial or full mobilization of contracted 

resources, including, but not limited to, skimming vessels, oil storage vessels, dispersant aircraft, 

subsea dispersant, 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, within 30 hours (based on the equipment‘s Estimated 

Daily Response Capacity (EDRC)). Shell will continue to ramp up additional on-water mechanical 

recovery resources as well as apply dispersants and in-situ burning as needed and as approved 

under the supervision of the USCG Captain of the Port (COTP) and the Regional Response Team 

(RRT).

Subsea Control and Containment: Shell, as a founding member of the MWCC, will have access 

to the IRCS that can be rapidly deployed through the MWCC. The IRCS is designed to contain oil 

flow in the unlikely event of an underwater well blowout, and is designed, constructed, tested, and 

available for rapid response. Shell‘s specific containment response for MC 525 will be addressed in 

Shell‘s NTL 2010-N10 submission at the time the APD is submitted.

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 323,500 

barrels/day. Temporary storage associated with the identified skimming and temporary storage 

equipment equals approximately 297,900 barrels.

De-rated Recovery Rate

(bopd)

Storage

(bbls)

Offshore Recovery and 

Storage 269,031 293,000

Nearshore Recovery and 

Storage 54,470 4,924

Total 323,501 297,924

Table 9.D.3 Mechanical Recovery Combined De-Rated Capability

Table 9.D.4 Offshore On-Water Recovery and Storage Activation List

Table 9.D.5 Nearshore On-Water Recovery and Storage 5ctivation List

Oil Storage: The strategy for transferring, storing and disposing of oil collected in these recovery 

zones is to utilize two 150,000-160,000 ton (dead weight) tankers mobilized by Shell (or any other 

tanker immediately available). The recovered oil would be transferred to Motiva‘s Norco, LA storage 

and refining facility, or would be stored at Delta Commodities, Inc. Harvey, LA facility.

Aerial Surveillance: Aircraft can be mobilized to detect, monitor, and target response to oil 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 approximately 

7,704 to 9,630 barrels of oil per day. Additionally, 3 to 4 sorties from the BE90 King Air and 3 to 4 

sorties from the Hercules C-130A within the first 12 hour operating day of the response could 

disperse 4,600 to 6,100 barrels of oil per day. For continuing dispersant operations, the CCA‘s Aerial 

Dispersant Delivery System (ADDS) would be mobilized. The ADDS has a dispersant spray capability 

of 5,000 gallons per sortie.

Table 9.D.7 Offshore Aerial Dispersant Activation 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 with 

two 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 (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 

and can make notification within 48 hours of the initial spill to begin ramping up fire boom 

production through contracted OSRO(s). There are potential limitations that need to be assessed 

prior to ISB operations. Some 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 ensure

that environmental and special economic resources would be correctly identified and prioritized to 

ensure optimal protection. Shell has access to shoreline response guides that depict the protection 

response modes applicable for oil spill clean-up 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.

D. Modeling Report

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

Figure 9.C.4 Pass a Loutre West ESI Map
Figure 9.C.5 Main Pass ESI Map
Table 9.D.4 Offshore On-Water Recovery and Storage Activation List
Table 9.D.4 Offshore On-Water Recovery and Storage Activation List (continued)

Table 9.D.4 Offshore On-Water Recovery and Storage Activation List (continued)
Table 9.D.5 Nearshore On-Water Recovery and Storage Activation List
Table 9.D.5 Nearshore On-Water Recovery and Storage Activation List (continued)

Table 9.D.6 Aerial Surveillance Activation List
Table 9.D.7 Offshore Aerial Dispersant Activation List

Table 9.D.8 Offshore Boat Spray Dispersant Activation List
Table 9.D.9 Control, Containment, and Subsea Dispersant Package Activation List
Table 9.D.10 In-Situ Burn Equipment Activation List
Table 9.D.10 In-Situ Burn Equipment Activation List (continued)

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

Management Service:

NTL 2007-G03 ―Marine Trash and Debris Awareness and Elimination‖

NTL 2007-G04 ―Vessel Strike Avoidance and Injured/Dead Protected Species Reporting‖

C. Flower Garden Banks National Marine Sanctuary

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

Banks and Stetson Bank.
SECTION 11: LEASE STIPULATIONS INFORMATION

Lease OCS-G 31507 was acquired in Lease Sale #205 with an effective date of March 1, 2008. The Lease is in its

primary term and will expire February 28, 2018.

Stipulation No. 3 – Military Areas

This lease is not in the Water Test Area of the Eglin Water Test Area 1. Shell will hold and save harmless the U.S. 

Government, its contractors and subcontractors, or any of its officers, agents or employees with regard to this 

Lease. Electromagnetic emissions will be conducted as to not interfere with the 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. 8 – Protected Species

This Stipulation is addressed in the following sections of this plan:

Section 6h, Threatened or endangered species, critical habitat, and marine mammal information

Section 10b, Environmental Monitoring Information, Incidental takes

Section 12b, Environmental Mitigation Measures Information, Incidental takes

Section 18, Environmental Impact Assessment

SECTION 12: ENVIRONMENTAL MITIGATION MEASURE INFORMATION

A. Impacts to Marine and coastal environments

The proposed action will implement mitigation measures required by laws and regulations, including all 

applicable Federal and State requirements concerning air emissions, discharges to water, and solid waste 

disposal, as well as any additional permit requirements and Shell policies. Project activities will be conducted in 

accordance with the Regional Oil Spill Response Plan. Section 18 of this plan discusses impacts and mitigation 

measures.

B. Incidental Takes

We do not anticipate any incidental takes related to the proposed operations. Shell implements the mitigation 

measures and monitors for incidental takes of protected species according to the following notices to lessees 

and operators from the BOEM:

NTL 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 EP as such information is only necessary in the case of 

DOCDs. 
SECTION 14: SUPPORT VESSELS AND AIRCRAFT INFORMATION

A. General 

Type Maximum Fuel Tank 

Storage Capacity (Gals)

Maximum No. In Area at 

Any Time

Trip Frequency or 

Duration

Crew Boats 8,000 2 Twice per week

Offshore Support Vessels 120,000 3 Twice per week

Helicopter 764 1 Once per day

B. Diesel Oil Supply Vessels

Size of Fuel Supply 

Vessel

Capacity of Fuel Supply 

Vessel

Frequency of Fuel 

Transfers

Route Fuel Supply Vessel Will 

Take

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

C. Drilling Fluids Transportation

This Plan does not propose activities in the State of Florida; therefore the following table is not 

required. It is being provided for information only.

Type of Material Quantity Being Transported Transportation Method

Dry Bulk (Cement, Barite, 

Gel)

12,000 sx max combined Below deck dry bulk tanks 

onboard OSV

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

boat

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

onboard OSV

D. Solid and Liquid Wastes Transportation

See Section 7, Table 7B.

E. Vicinity Map

See Attachment 14-A for vicinity map.
SECTION 15: ONSHORE SUPPORT FACILITIES INFORMATION

A. General 

Name Location Existing/New/Modified

Fourchon Port Fourchon, LA Existing

Amelia PHI Heliport Amelia LA Existing

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

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

south of Leeville, LA approximately 3 miles from the Gulf of Mexico. The existing onshore air support 

base in Amelia, LA is located at 4008 Lake Palourde Road, Amelia, LA 70340.

B. Support Base Construction or Expansion

This Section does not apply to this EP as Shell does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP.

C. Support Base Construction or Expansion Timetable

This Section does not apply to this EP as Shell does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP.

D. Waste Disposal

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

E. Air emissions

Not required by BOEM GOM.

F. Unusual solid and liquid wastes

Not required by BOEM GOM.

SECTION 16: SULPHUR OPERATIONS INFORMATION

Information regarding Sulphur Operations Information is not included in this EP as we are not proposing to 

conduct sulphur operations.
SECTION 17: COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION

LOUISIANA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

INITIAL EXPLORATION PLAN

Type of Plan

MISSISSIPPI CANYON Block 525

Area and Blocks

OCS-G 31507

Lease Number

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal 

Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management 

Enforceable Policies. 

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

SHELL OFFSHORE INC.

Operator

_____________________________________________

Sylvia A. Bellone

Certifying Official

 9/30/2011

Date
ALABAMA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

INITIAL EXPLORATION PLAN

Type of Plan

MISSISSIPPI CANYON Block 525

Area and Blocks

OCS-G 31507

Lease Number

The proposed activities described in detail in this Plan will comply with 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 Louisiana's Enforceable Policies in making this certification of consistency.

SHELL OFFSHORE INC.

Operator

____________________________________________

Sylvia Bellone

Certifying Official

 9/30/2011

Date
Coastal Zone Management Consistency Information

For the State of Alabama

In accordance with 30 CFR 250.226(a) and (b), Shell Offshore Inc. (SOI) is hereby providing the 

following information in support of Section 18 (Environmental Impact Analysis) of our Exploration Plan for 

this lease. 

The regulations found in 15 CFR 930.58 identifies necessary data and 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 EP.

B. OTHER INFORMATION

(1) Shell Offshore Inc. shall utilize a shore base in Fourchon, Louisiana for water support and 

PHI‘s Amelia terminal for air traffic for the proposed activities. 

(2) As per NTL 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 EP.

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

proposed activities and associated facilities to the relevant enforceable policies of the

Alabama‘s Coastal Management Program:

All activities shall 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 MMS 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 Amelia, 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, constructed

operated and maintained to avoid to the maximum extent practicable adverse alteration of 

biologically valuable areas. All uses and activities shall be planned, sited, designed, 

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

in long-term biological productivity of the coastal ecosystem. No impacts are expected to 

adversely affect the biological productivity of the area.

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

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 MMS regulations, the USEPA‘s NPDES general permit, and the 

USCG regulations implementing MARPOL 73/78 Annex V prohibit the disposal of any trash 

and debris into the marine environment. 

Water Resources - All uses and activities shall be planned, sited, designed, constructed 

operated and maintained to avoid to the maximum extent practicable detrimental discharges 

into coastal waters.

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

quality laws, standards, and regulations. Emissions from the proposed activities are not 
expected to have significant impacts on onshore air quality because of the prevailing 

atmospheric conditions, emission heights, emission rates, and the distance of these 

emissions from the coastline.

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 DOCD. Proposed activities are not expected to have 

any adverse impact on sea grass communities. 

Beach and Dune Protection - Effective environmental protection plans are in place, practiced, 

and updated as necessary. No significant impacts to the physical shape and structure of 

barrier beaches and associated dunes are expected to occur. In the unlikely event of a spill 

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 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 adverse 

alteration of cultural resources. No impacts are expected to adversely affect historical, 

architectural, or archaeological sites. Should any historical, architectural, or archaeological 

resource be 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)

1.0 Introduction

1.1 Project Summary

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

Block 525, wells A, B, C, D, and E. This initial EP is being submitted pursuant to Lease Sale 205, which 

was approved by the U.S. Department of the Interior (USDOI), Minerals Management Service (MMS, now 

Bureau of Ocean Energy Management [BOEM]) on October 3, 2007. This Initial EP was prepared in 

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

2010-N06 that requires an updated blowout scenario and calculation of the worst case discharge (WCD).

MC Block 525 is 79 statute miles1(127 kilometers [km]) from the nearest shoreline; 164 miles (264 km) 

from the onshore support base at Port Fourchon, Louisiana; and 208 miles (167 km) from the helicopter 

base at Amelia, Louisiana (Figure 1). The proposed wellsites are in water ranging from 7,400 to 

7,600 feet (2,255 to 2,316 meters [m]) deep.

Shell proposes to use the Noble Globetrotter or a similar dynamically positioned (DP) drillship for this 

project, beginning in the second quarter of 2012. The first well is expected to take 148 days to drill, and 

each additional well would take about 128 days to drill. 

1.2 Purpose of the EIA

The purpose of this Environmental Impact Analysis (EIA) is to evaluate the potential effects of the 

proposed action on environmental resources in the project area. The EIA was prepared pursuant to the 

National Environmental Policy Act (NEPA) and other federal laws, including the Outer Continental Shelf 

Lands Act (OCSLA), the Endangered Species Act (ESA), the Marine Mammal Protection Act (MMPA), the 

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

associated with these laws. 

Shell has prepared this EIA in accordance with NTL 2008-G04 and subsequent guidance to provide 

necessary information to support BOEM‘s approval of the Initial EP for proposed activities in MC Block 

525. 

1.3 Related Environmental Documents

NEPA regulations stipulate that broad programmatic Environmental Impact Statements (EIS) form the 

foundation used to tier more focused project-specific analyses (40 Code of Federal Regulations [CFR.] § 

1508.28). BOEM has prepared three broad EISs for oil and gas drilling activities in the project area: 

(1) Outer Continental Shelf Oil & Gas Leasing Program: 2007-2012 Final EIS (MMS 2007a), (2) the 

Multisale EIS (Gulf of Mexico OCS Oil and Gas Lease Sales: 2007-2012; Western Planning Area Sales 204, 

207, 210, 215, and 218; Central Planning Area Sales 205, 206, 208, 213, 216, and 222; Final EIS) (MMS 

2007b); and (3) the Multisale Supplemental EIS (Gulf of Mexico OCS Oil and Gas Lease Sales: 2009-2012; 

Central Planning Area Sales 208, 213, 216, and 222; Western Planning Area Sales 210, 215, and 218; 

Final Supplemental EIS [SEIS]) (MMS 2008). In addition, BOEM has recently published a final SEIS for 

the Western Planning Area (Gulf of Mexico OCS Oil and Gas Lease Sale: 2011; Western Planning Area 

Lease Sale 218 Final Supplemental Environmental Impact Statement) (BOEM 2011a) that provides 

updates to the environmental conditions and impacts since the Deepwater Horizon (DWH) event. The 

2011 SEIS provided a thorough analysis of conditions within the northern Gulf of Mexico that may have 

 

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

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

extent that the BOEM (2011a) SEIS addresses conditions that prevail within the project area for this 

proposed action, it is incorporated by reference. 

MC 525 is in deepwater Grid 17; no Grid Environmental Assessment (EA) was prepared for Grid 17. 

However, a recently prepared site-specific EA (SEA) for exploratory activities in nearby lease blocks is 

considered relevant to this EIA because it addresses similar work in the project vicinity (BOEM 2011b). 

Moreover, the SEA includes information not available during the preparation of the Multisale and 

Supplemental EISs (MMS 2007a, b; 2008), particularly with respect to the DWH event.

The purpose of tiering NEPA documents is to streamline or focus the project-specific analysis on aspects 

of the proposed action (1) that differ from the overall program, or (2) for which assumptions have 

changed since the programmatic documents were prepared. The purpose of NEPA analysis, which is to 

provide a thorough, transparent evaluation of potential project-related impacts to resources, is best 

served by smaller, simpler documents that focus directly on the relevant environmental issues. Wherever 

a programmatic EIS adequately addresses potential site-specific impacts, it is incorporated by reference 

to avoid repetitive discussion. 

The programmatic EISs evaluate the potential effects of leasing, exploration, development, and related 

activities on the environmental, archaeological, and socioeconomic resources of the Gulf of Mexico in 

general. Particular aspects of the living environment that may be affected by activities in the Outer 

Continental Shelf (OCS) include offshore benthic resources, fish and fisheries, sea turtles, coastal and 

marine birds, marine mammals, endangered and threatened species, and sensitive coastal environments. 

Over the past several decades, BOEM and others have conducted numerous technical studies focused on 

describing baseline conditions, predicting the outcome of routine operations and accidental releases, and 

developing mitigation measures to minimize adverse effects. Through this process, BOEM has developed 

permit and lease stipulations, mitigation measures, and standard operating procedures and requirements 

that promote the protection of resources during exploration and development of offshore wells. This sitespecific EIA incorporates OCS mitigation measures both implicitly and explicitly so that the proposed 

action can be carried out with minimal impact to the environment.
Figure 1. Project Location: MC 525
1.4 OCS Regulatory Framework

As a regulatory agency of the USDOI, BOEM manages and regulates offshore activities as directed by 

OCSLA (30 CFR 250, 251, and 254). In addition to its regulatory function, BOEM manages the 

Environmental Studies Program, envisioned in OSCLA as a mechanism to ―monitor the human, marine, 

and coastal environments of such area or region in a manner designed to provide time-series and data 

trend information...‖ (Matthews and Cameron 2010; page 2). Ongoing environmental studies focus on oil 

spill trajectories, impacts of anchoring, sensitive chemosynthetic communities, and other aspects of OCS 

activities. 

Both OCSLA and NEPA require that BOEM consult or cooperate with other federal and state agencies with 

jurisdiction over public resources. Federal laws requiring interagency cooperation include the Coastal 

Zone Management Act of 1972 (CZMA), the ESA of 1973, MSFCMA, and MMPA. The purpose of these 

laws is to ―encourage orderly, safe, and environmentally responsible development of oil, natural gas, and 

alternative energy sources on the OCS,‖ as described in the OCS Regulatory Framework for the Gulf of 

Mexico Region (Matthews and Cameron 2010, page 1). The BOEM interacts routinely with the U.S. Coast 

Guard (USCG), U.S. Environmental Protection Agency (EPA), U.S. Fish and Wildlife Service (FWS), and 

the National Oceanic and Atmospheric Administration (NOAA), specifically the National Marine Fisheries 

Service (NMFS). 

The BOEM provides explicit instruction to operators through NTLs, which are ―formal documents that 

provide clarification, description, or interpretation of a regulation or OCS standard; provide guidelines on 

the implementation of a special lease stipulation or regional requirement; provide a better understanding 

of the scope and meaning of a regulation by explaining BOEM interpretation of a requirement; or transmit 

administrative information...‖ (BOEM 2011c). Seven NTLs are considered pertinent to this EIA (Table 1). 

1.5 Oil Spill Prevention and Contingency Planning

Shell submitted an update to the Gulf of Mexico Regional Oil Spill Response Plan (OSRP) to the BOEM as 

a fundamental component of the planned drilling program. The OSRP certifies that Shell has the 

capability to respond to the maximum extent practicable to a WCD (30 CFR 254.2) (see Initial EP Section 

9). The OSRP demonstrates Shell‘s capabilities to rapidly and effectively manage oil spills that may result 

from drilling operations. 

A large oil spill is extremely unlikely to be associated with the proposed action. However, Shell‘s OSRP 

provides contingencies for a range of spills, from small operational spills up to and including a WCD from 

a well blowout. Shell‘s OSRP demonstrates the capacity to respond to a large oil spill that exceeds the 

calculated WCD for the proposed action. Shell‘s OSRP meets or exceeds federal requirements and 

regulations of each of the potentially affected Gulf Coast states. The OSRP is incorporated by reference 

to this EIA.

Shell has calculated a WCD for this Initial EP, using the requirements prescribed by NTL 2010-N06, as 

271,000 barrels of oil per day (BOPD) for the first day with a 30-day average of 233,000 BOPD. The 

detailed analysis of this calculation can be found in Initial EP Section 2j. The WCD scenario for this 

Initial EP, in terms of both initial and the sustained rates, has a low probability of being realized. Several 

factors that are likely to reduce rates and volumes of released oil are not included in the WCD calculation, 

including obstructions or equipment in the wellbore, well bridging, and early intervention such as 

containment. 
Table 1. Notices to Lessees and Operators (NTLs) Pertinent to this EIA

NTL Title Summary EIA

Section

2010-N10

Statement of 

Compliance with 

Applicable Regulations 

and Evaluation of 

Information 

Demonstrating 

Adequate Spill 

Response and Well 

Containment Resources

Requires that applications for well permits certify 

that the operator (Shell) will comply with all 

applicable regulations, including the increased 

safety measures regulations particularly regarding 

subsea blowout preventers (BOP) or surface BOPs 

on floating facilities. BOEM evaluates whether the 

application demonstrates the operator‘s ability to 

rapidly deploy containment resources in the event 

of a blowout or other uncontrolled discharge.

2.2.2 

2010-N06

Information 

Requirements for 

Exploration Plans, 

Development and 

Production Plans, and 

Development 

Operations Coordination 

Documents on the OCS

Provides guidance on calculating the worst case 

discharge, superseding NTL 2008-G04.

1.5

2.2.2

4.13

2009-G40 Deepwater Benthic 

Communities

Instructs operators to avoid and protect highdensity deepwater benthic communities 

(particularly chemosynthetic and deepwater coral 

communities) during exploration and production in 

water depths greater than 984 feet (300 m). 

Requires a buffer of 2,000 feet (610 m) around 

mud and cuttings discharge locations and 250 feet 

(76 m) around all other seafloor disturbances.

4.4

2008-G04

Information 

Requirements for 

Exploration Plans and 

Development 

Operations Coordination 

Documents

Provides guidance on the contents of OCS plans, 

including the EIA. 

2.0

2007-G04

Vessel Strike Avoidance 

and Injured/Dead 

Protected Species 

Reporting

Directs operators to consider training vessel crews 

to recognize and avoid protected species, 

especially marine mammals and sea turtles, and to 

report sightings of any dead or injured protected 

species.

4.6.4 

4.8.1.4

4.8.3.4

4.8.4.4

4.13.4.1

2007-G03

Marine Trash and 

Debris Awareness and 

Elimination

Directs operators to properly dispose of trash and 

debris that may enter the marine environment; 

requires informational placards on offshore vessels 

and structures; requires annual training in proper 

handling of marine trash and debris.

2.1.7

4.5

4.6.2

4.8.1.1

4.8.4.2

4.12.3

2005-G07 Archaeological Resource 

Surveys and Reports

Interprets regulations on documenting and 

protecting archaeological discoveries, performing 

resource surveys, and preparing reports.

4.11.1

2009-G06 Military Warning and 

Water Test Areas

Provides instructions for communication with 

command headquarters for military warning and 

water test areas in the Gulf of Mexico. Lessees are 

required to coordinate the use of vessel and 

4.12.6
NTL Title Summary EIA

Section

aircraft and to report electromagnetic emissions in 

the applicable warning area or water test area. 

1.6 EIA Organization

This EIA provides all of the information requested in NTL 2008-G04 as well as the NTLs listed in Table 1. 

Section 2.0 introduces the potential impact-producing factors associated with the proposed action. 

Section 3.0 briefly describes alternatives considered in developing the proposed action. Section 4.0 

describes the affected environment, largely by incorporating existing analyses prepared for the central 

Gulf of Mexico, and evaluates the impacts of the proposed action on environmental, archaeological, and 

socioeconomic resources; it also includes a discussion of cumulative impacts. Section 5.0 discusses 

environmental hazards, including geologic hazards, severe weather, and currents and waves. Mitigation 

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

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

2.0 Potential Impact Producing Factors

The BOEM‘s programmatic EISs evaluated an extensive list of potential OCS activities that could adversely 

affect resources in and near the project area (MMS 2007a, b; 2008; BOEM 2011a). The proposed plan 

would include only a few of the activities evaluated in the programmatic EISs. BOEM recommends that 

the EIA include a matrix of impact-producing factors (IPF) and resources, outlined in NTL 2008-G04, to 

streamline the analysis of potential project-specific impacts. 

Potential IPFs of the proposed action may result from both routine and accidental events. Routine IPFs 

associated with the proposed action may include (1) noise and lights, (2) physical disturbance of the 

seafloor, (3) water intake, and (4) effluent (Table 2). Accidental IPFs include (1) small fuel and chemical 

spills, (2) a large oil spill, and (3) vessel strikes (Table 3). Onshore waste disposal and marine debris 

were determined not to be IPFs for the proposed action. Detailed analysis of potential and actual IPFs is 

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

Potential Impact-Producing Factor*

Environmental 

Resources

Noise/Lights

(drillship and 

support vessels)

(Section 2.1.1)

Physical 

Disturbance

(drillship and 

support vessels)

(Section 2.1.2)

Water 

Intake

(drillship)

(Section 

2.1.3)

Effluent

(drillship)

(Section 

2.1.4)

Air 

Emissions

(Section 

2.1.5)

Air Quality X

Water Quality X

Seafloor Communities X X

Lower Trophic Levels X

Fisheries X X X X

Sea Turtles X X X

Sea Birds X X X

Marine Mammals X X X

Commercial and 

Recreational Fishing 

X X

Note: 

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

See Section 4.0 for a complete description of the resources listed here.

*Potential IPFs that were determined not to adversely affect resources under the proposed action include 

onshore waste disposal (Section 2.1.6) and marine debris (Section 2.1.7). 

2.1 IPFS Associated with Routine Activities

Routine activities that may affect environmental resources include (1) lights and noise, (2) physical 

disturbance of the water column and seafloor, (3) air emissions, (4) water intake, and (5) discharge of 

effluent. Other potential IPFs resulting from routine activities that are not expected to cause any impacts 

include onshore waste disposal and marine debris. 

2.1.1 Noise and Lights

The proposed action would introduce noise and lights to the project area associated with the drillship, 

support vessels, and helicopters (MMS 2000, Thomsen and others 2011). The Noble Globetrotter, or a 

similar DP drillship, would be on site for about 148 days to drill the initial exploration well, then an 

additional 128 days for each of the subsequent wells. Three offshore support vessels and a helicopter 

would make regular trips to the project site as necessary. 

The drillship would add noise to the environment as it uses propellers and thrusters to mobilize and hold 

its position; shipboard generators and drilling machinery would create additional noise. Drilling can 

generate unidirectional noise with a bandwidth between 10 and 1000 Hertz (Hz); the main energy is 

focused in the 30 to 60 Hz range (Thomsen and others 2011). Support vessels and helicopters would 

travel to and from the drillship daily, adding transient noise to the immediate environment as they pass 

by. 

In addition to noise, the drillship would also add nearly constant artificial light sources to the project area. 

Vessels and helicopters traveling at night would introduce transient light sources to the immediate area.

The lights are required for safety and navigation but are considered potential IPFs for seabirds and 

marine animals. The impacts of noise and lights on biological resources are discussed as appropriate in 

Section 4.5 (Fish, Fisheries, and Essential Fish Habitat), 4.6 (Sea Turtles), 4.7 (Coastal and Marine Birds), 

and 4.8 (Marine Mammals).

2.1.2 Physical Disturbance of the Water Column and Seafloor

The drillship would be in open water in the project area for a period of several months. The presence of 

the DP drillship would not cause any adverse effects to environmental resources. The drillship may 
inadvertently function as a fish-attracting or fish-aggregating device (FAD), meaning that pelagic fish, 

especially tuna, may congregate near it. 

The Noble Globetrotter and similar drillships use thrusters rather than anchors to maintain position while 

they drill a well. The only anticipated disturbance of soft bottom communities of the seafloor would 

result from the positioning of the wellbore and the BOP. Once the wellbore is in place, mud and drill 

cuttings would be deposited in the immediate vicinity of the wellbore.

2.1.3 Water Intake

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

firewater and once-through, non-contact cooling of machinery on the drilling rig. Water intakes can 

impinge or entrain pelagic organisms, leading to injury or mortality. Under Section 316(b) of the Clean 

Water Act, cooling water intakes must use the best technology available (BTA) to minimize impingement 

and entrainment of organisms. EPA recently expanded the Section 316(b) regulations to include ―new, 

non-fixed‖ facilities such as the Noble Globetrotter (implemented via EPA NPDES General Permit GMG 

290000). The Noble Globetrotter will be in full compliance with the BTA requirements specified in the 

NPDES permit.

2.1.4 Effluent Discharges

Shell discharges effluent offshore in compliance with EPA General Permit No. GMG 290000 under the 

National Pollutant Discharge Elimination System (NPDES). All effluents would be discharged as required 

by the permit (see Initial EP Section 7). 

Effluents would include water-based drilling mud and cuttings, excess cement slurry, synthetic-based 

mud (SBM), water-based blowout prevention fluid, treated bilge water, treated chemical product waste, 

non-contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, 

uncontaminated fire water and ballast water (see Table 7a in Initial EP). The potential impacts of 

these effluents are discussed in Sections 4.2 (Water Quality), 4.4 (Deepwater Benthic Communities), and 

4.5 (Fish, Fisheries, and Essential Fish Habitat). 

Cuttings would be discharged and at the seafloor as the initial well intervals are being installed. Once the 

marine riser is set, cuttings would be returned to the surface. Excess cement slurry produced when the 

casing is being installed during the riserless portion of the operation would be discharged at the seafloor.

Once the riser is installed, an SBM system would be used. The SBM would be recovered for recycling at 

an onshore facility. SBM cuttings would be discharged overboard only when the SBM interval is being 

drilled. Those cuttings would first be treated to reduce retention of SBM fluid to less than 6.9 percent 

(the maximum allowable under the NPDES permit). Discharges of cleaned SMB drill cuttings are 

addressed in Initial EP Table 7a). 

2.1.5 Air Emissions

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

described in Initial EP Section 8. Air emissions from diesel combustion include suspended particulate 

matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCs), and carbon 

monoxide (CO).

Shell prepared an Air Quality Emissions Report following BOEM guidance. Estimated emissions for the 

drillship are below exemption levels and are not expected to significantly affect onshore air quality for 

any of the criteria pollutants (30 CFR 250.303). Although no additional modeling or mitigation measures 

are required, it is Shell‘s standard procedure to further reduce emissions by using low-sulfur fuel. Air 

emissions resulting from an accidental spill are discussed in Section 2.2. 
2.1.6 Onshore Waste Disposal

The proposed action will generate Exploration & Production (E&P) waste (Initial EP Section 7) which

will be collected and disposed of at Newpark Environmental Services or U.S. Liquids of Louisiana (both in 

Fourchon, Louisiana). Nonhazardous trash and debris and non-recyclable waste will be transported to

the Republic/BFI landfill in Sorrento, Louisiana, or the parish landfill in Avondale, Louisiana. 

Nonhazardous recyclable waste, including used oil, glycol, oil filters, oily rags and pads, empty drums, 

and cooking oil, will be recycled at Omega Waste Management, West Patterson, Louisiana, or at ARC of 

New Iberia, New Iberia, Louisiana. Hazardous waste (paints, solvents, and unused chemicals) will be 

transported to Safety Kleen Systems, Inc., in Denton, Texas. Universal waste such as batteries, lamps, 

glass, and mercury-contaminated waste will be disposed of at Lamp Environmental Industries in 

Hammond, Louisiana. Wastes will be recycled or disposed of in compliance with all applicable 

regulations. Although onshore waste disposal is a potential IPF, Shell‘s standard procedures reduce the 

IPF to non-significant levels under the proposed action. 

2.1.7 Marine Debris

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

Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements, federal 

regulations, and BOEM‘s NTLs on solid wastes. Operators may not purposefully discard trash or debris 

overboard into the marine environment (30 CFR 250.300[a] and [b] [6]). To discourage illegal dumping, 

federal regulations require that all equipment, tools, and containers (such as drums) be marked with 

permanent identification (30 CFR 250.300[c]). As required by EPA and USCG, Shell has prepared a waste 

management plan and posted informational placards on vessels. Shell instructs all personnel to cover 

trash bins, document trash sent ashore, and minimize solid waste in general. Shell‘s plan incorporates 

the guidance in NTL 2007-G03, directing personnel to retain waste packaging and small disposable items, 

providing visual reminders in prominent locations on vessels and structures, and requiring annual 

educational refresher courses on the importance of minimizing marine debris. Shell‘s management plan 

and staff training programs effectively minimize the potential for marine debris to be an IPF for the 

proposed action. 

2.2 Potential IPFS Associated with Accidents

Impacts to environmental, archaeological, and socioeconomic resources were analyzed for three types of 

accidental events: (1) a small fuel or chemical spill (less than 1,000 bbl), (2) a large spill, and (3) vessel 

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

Section 4.0.
Table 3. Potential IPFs Associated with Accidents under the Proposed Action

Potential Impact-Producing Factors

Resources

Small Fuel or 

Chemical Spill 

Large Oil Spill Vessel Strikes 

(boats and 

helicopters)

Environmental Resources

Air Quality X X

Water Quality X X

Offshore Biological Resources

Seafloor Communities X

Chemosynthetic Communities X

Lower Trophic Levels X X

Fish, Fisheries, and Essential Fish Habitat X X

Sea Turtles X X X

Seabirds X X X 

Marine Mammals X X X 

Coastal Biological Resources

Diamondback Terrapin X X

Shorebirds X X

Beach Mouse X X

Coastal Habitats X X

Coastal Wildlife Refugia X X

Archaeological Resources

Shipwrecks X

Prehistoric sites X

Socioeconomic Resources

Recreational Fishing X X

Non-fishing Recreational Activities X X

Coastal Employment X

Land Use X

Notes:

*See Section 4.0 for a complete description of the resources listed here. 

Environmental resources that would not be adversely affected by accidental events under the proposed 

action include pinnacles and other sensitive topographic areas and Eastern Gulf live bottom habitats. 

2.2.1 Small Fuel or Chemical Spill

Shell‘s OSRP focuses on (1) prevention, (2) response, and (3) cleanup, as detailed in the OSRP. This 

combined effort makes it exceedingly unlikely that a small fuel or chemical spill would cause any 

significant impact beyond a transient effect on the immediate localized area. Shell‘s approach to 

minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 9b.

A small fuel spill is the most likely type of spill to result from the proposed action, based on the history of 

exploration and development activities in the OCS. The Multisale EIS concluded that a minor diesel spill 

(less than 1 bbl) is the most likely type of accident to occur during typical offshore activities (MMS 

2007b), and that ―moderately‖ sized spills (up to 1,000 bbl) would occur infrequently (BOEM 2011a). 

Most small spills result from a ruptured hose during fuel transfer and release no more than 3 bbl of diesel 

into the water (MMS 2007b). Spills of less than 1,000 bbl are not expected to persist long enough to 

reach the shoreline, but may cause temporary effects to offshore resources (BOEME 2011a). Impacts of a 

small spill are discussed in Section 4.0 for each resource. 
2.2.2 Large Oil Spill

An uncontrolled flow of a reservoir fluid may release gas, condensate, oil, drilling fluids, sand, or water 

into the environment. ―Loss of well control‖ refers generally to both minor and serious well control 

incidents. A serious loss of well control with a greater risk of oil spill or human injury is called a 

―blowout‖ (MMS 2007b). Following the guidance provided in NTL 2010-N06, Shell calculated that 

271,000 bbl could be discharged during the first day of a blowout, with a 30-day average of 233,000 

BOPD under the proposed action. During the 157 days it could take to drill a relief well, a total volume of 

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

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

referenced WCD.

The WCD scenario for this Initial EP, in terms of both initial and the sustained rates, has a low probability 

of being realized. The WCD calculation is based on the co-occurrence of multiple highly-unlikely 

assumptions, and does not include any response actions (International Association of Oil & Gas Producers 

2011). Obstructions or equipment in the wellbore, well bridging, and early intervention would reduce the 

actual rate of discharge and volume of a spill to less than the calculated WCD.

Shell‘s well control and blowout prevention measures, described in Initial EP Section 2j, are focused on 

minimizing a blowout that would cause a large spill. By definition, the WCD is an exceedingly unlikely 

event. Shell‘s focus on safety and precaution, coupled with its commitment to rapid response, further 

reduces the probability that a large spill will occur, as described in Initial EP Section 2j. Shell has 

aggressively developed policies and procedures to prevent blowouts, minimize the discharge resulting 

from a blowout, and contain the product resulting from a discharge. Shell‘s response to NTL 2010-N06 

and compliance with NTL 2010-N10 and the Interim Final Drilling Safety Rule are detailed in Initial EP 

Sections 2j and 9b. 

Notwithstanding the recent DWH event, blowouts during deepwater exploratory drilling remain 

exceedingly rare in the Gulf of Mexico. Between 1992 and 2005, less than 10 percent of all blowouts in 

the Gulf of Mexico caused releases of oil, and most blowouts lasted less than 12 hours (MMS 2007b). 

More recent estimates of blowout probabilities are even lower because of increased awareness and 

enhanced safety equipment (BOEM 2011b, d). 

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

at the time would influence the ultimate trajectory of the oil. A quantitative spatial Oil Spill Risk Analysis 

(OSRA) model incorporating winds and current data in the project area estimates conditional contact 

probabilities for shoreline segments (Ji and others 2004). The OSRA model predicts that a spill in the 

proposed action area (Launch Area 57; MC 525) would not result in shoreline contact during the first 10 

days. After 30 days, oil could reach six Louisiana parishes, three Mississippi counties, three Alabama 

counties, and three Florida counties. The greatest likelihood of contact within 30 days (21 percent) is in 

Plaquemines Parish, Louisiana (Ji and others 2004) (Table 4).
Table 4. Conditional Probabilities of Shoreline Contact

Shoreline 

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

C13 Cameron, Louisiana 1

C14 Vermilion, Louisiana 1

C17 Terrebonne, Louisiana 2

C18 Lafourche, Louisiana 2

C20 Plaquemines, Louisiana 21

C21 St. Bernard, Louisiana 3

C22 Hancock & Harrison, Mississippi 1

C23 Jackson, Mississippi 1

C24 Mobile, Alabama 1

C25 Baldwin, Alabama 1

C26 Escambia, Alabama 1

C28 Okaloosa, Florida 1

C29 Walton, Florida 1

C30 Bay, Florida 1

Source: Ji and others (2004)

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

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

than 0.5 percent. 

The OSRA model represents an uncontained 30-day spill in the absence of any response action. It does 

not take into account the environmental fate of the oil once it is released, such as weathering and 

microbial degradation (Ji and others 2004). 

As demonstrated by the DWH event, the fate of oil released into the Gulf of Mexico would be greatly 

affected by human intervention. Shell‘s spill response, as described in the OSRP and summarized in 

Initial EP Sections 2j and 9b, would minimize the volume of a spill that would ultimately make contact 

with the shoreline. In the updated OSRP, Shell certified that it was capable of responding to a spill larger 

than the calculated WCD for the proposed action. 

Since the DWH event, Shell and other operators In the Gulf of Mexico have developed an integrated 

subsea well control and containment system deployed through the Marine Well Containment Company 

(MWCC), a non-profit organization that coordinates and assists with responses to large spills. Shell has 

full access to all of the resources available through MWCC for subsea containment of an unplanned 

release. Through the MWCC and other resources, Shell is compliant with all the requirements of 

NTL 2010-N10. Other resources include the Clean Caribbean & Americas (CCA), Marine Spill Response 

Corporation (MSRC), Clean Gulf Associates (CGA), and Oil Spill Response Limited (OSRL). As an active 

member of these and other organizations, Shell has access to equipment and personnel needed for spill 

response. Shell also supports development of new technology and procedures to respond to accidental 

releases, based on experience with the DWH event. Because of the lessons learned during the response 

to that event, Shell is substantially better prepared today to respond to a large spill. Additional details on 

Shell‘s extensive commitment to spill containment and cleanup are in the OSRP.

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

Offshore On-Water Recovery Activation List in Shell‘s OSRP. In the event that dispersants are needed, 

Shell has agreements in place with suppliers in the Gulf States such as MSRC in Texas, Louisiana, 

Mississippi, and Florida; MWCC; CGA/Airborne Support, Inc. (ASI) in Louisiana and Texas; and Clean 

Caribbean and Americas in Florida. Additional supplies are available from international vendors. Under 

certain conditions, open-water in situ burning may be a suitable control strategy (USCG 2009). Shell is 

prepared to deploy trained burn crews if the situation warrants such a response. 
Separate and apart from a dedicated human response to a large oil spill, natural processes such as 

weathering and biodegradation would work to reduce the volume and alter the characteristics of spilled 

oil. Oil begins to weather as soon as it is released to the environment, losing up to 23 percent of its 

volume within the first 2 hours under certain conditions (deGouw and others 2011). The lighter aromatic 

and aliphatic hydrocarbons are the first constituents of oil to enter the atmosphere, where there are 

quickly degraded by sunlight (Operational Science Advisory Team [OSAT]-2 2011). Weathering involves 

physical, chemical, and biological processes that alter the physical and chemical properties of the oil, 

reducing its toxicity to marine organisms. Physical weathering mechanisms include spreading, 

evaporation, dissolution, dispersion, emulsification, photochemical oxidation, and adsorption to 

suspended particulates. Ultimately, weathered oil may settle to the seafloor, where it becomes 

integrated with bottom sediments (NRC 2003). 

Microbial organisms native to the Gulf of Mexico degrade oil at the surface and in the water column by 

releasing the lighter aromatic portions of the oil (Atlas and Hazen 2011). Heavier components are more 

difficult to degrade and may persist in the environment for a longer time. Temperature, access to 

oxygen, and physical perturbation of the water affect the rate at which oil is consumed by microbes. 

Dispersants may accelerate microbial degradation under some conditions (Atlas and Hazen 2011) but 

inhibit degradation under other conditions (Hamdan and Fulmer 2011). Tracer studies showed that 

carbon from the oil spilled during the DWH event was quickly incorporated into the bodies of 

zooplankton, apparently through food chain transfer (Graham and others 2010). Evidence of the 

complex effects of dispersants on ecosystem processes is discussed in the WPA SEIS BOEM (2011a).

2.2.3 Vessel and Helicopter Strikes

Vessel collisions would be expected to occur infrequently during the course of the project. Most vessel 

collisions involve a boat and a platform or pipeline riser, which could result in a small fuel spill (MMS 

2007b). Only eight vessel collisions associated with oil and gas operations were reported to the BOEM in 

the entire Gulf of Mexico in 2010 (BOEM 2011e). However, vessels may also collide with marine 

mammals or sea turtles. The impact of each of these scenarios is discussed in Section 4.0.

Helicopter accidents involving drillships are extremely rare and not considered significant in this EIA. 

Helicopter collisions with birds are more likely but not considered to result in significant impacts because 

of the infrequency of helicopter use in the project area and the absence of threatened and endangered 

avian species in the vicinity. 

Shell will comply with all USCG- and BOEM-mandated safety requirements to minimize the potential for 

vessel collisions with structures and animals. Shell contracts directly with professional vessel operators, 

who are responsible for adhering to all federal regulations. As an additional level of support for the 

vessel operators, Shell maintains a 24-hour communication link for vessel operators to report any 

incidents. 

2.3 Hydrogen Sulfide

The proposed action is in an area where hydrogen sulfide (H2S) concentrations have not been 

characterized. Based on 30 CFR 250.490 (c), Shell has requested that the area where drilling operations 

are proposed be classified as having ―unknown‖ presence of H2S. 

3.0 Alternatives

No formal alternatives were evaluated in this EIA. However, Shell evaluated several alternative locations 

for wellsites, choices of drilling rigs and drillships, and other operational elements as part of the proposed 

action. The proposed action is within the range of activities evaluated as the preferred alternative in the 

Multisale EIS (MMS 2007b). Technical and logistical necessities precluded development of other 

alternatives that would accomplish the goals of this project. 
4.0 AFFECTED ENVIRONMENT and Impact Analysis

Water depths in the project area range from approximately 7,450 to 7,600 feet (2,270 to 2,316 m), 

according to the Geohazards Assessment report (Fugro GeoServices, Inc. 2002). The relatively flat 

seafloor is interspersed with hummocky areas (Figure 2). The overall gradient is less than 1° to the 

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

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

The affected environment of the northern Gulf of Mexico was described in detail in programmatic EISs 

(MMS 2007a,b, 2008; BOEM 2011a) and in a SEA prepared for an exploration plan in nearby lease blocks 

(BOEM 2011b), referred to as SEA S-7445. The affected environment in MC 525 is similar to that 

described in SEA S-7445, and the SEA is incorporated by reference. These NEPA documents reflect 

exhaustive reviews of the scientific literature, including recent information on impacts of the DWH event 

that is not yet available to the public. This section provides baseline information and impact assessment 

for environmental, biological, archaeological, and socioeconomic resources as well as a discussion of 

cumulative impacts.
Figure 2. Bathymetry and Proposed Well Surface Locations.
Principal environmental resources of concern include air quality (Section 4.1) and water quality (Section 

4.2). Biological resources addressed in this section include lower trophic level organisms, deepwater 

benthic communities (chemosynthetic and nonchemosynthetic), fish and fisheries, sea turtles, birds, 

marine mammals, and terrestrial animals, along with their habitats (Sections 4.3 through 4.10). 

Archaeological and socioeconomic resources are also addressed (Sections 4.11 and 4.12). 

NEPA regulations allow for, and even recommend, that project-specific EIAs be tiered from broad 

programmatic EISs. Baseline conditions of resources and potential impacts resulting from routine 

activities and accidental events have been extensively described in the programmatic EISs (MMS 2007b, 

2008), the EA for Gulf of Mexico deepwater operations and activities (MMS 2000), and SEA S-7445

(BOEM 2011b); these documents are incorporated by reference in this tiered EIA. Accordingly, 

description of the affected environment and potential impacts in this EIA is limited to new or site-specific 

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

impacts relevant to the proposed action.

An analysis of the significance of impacts under NEPA requires consideration of both context and intensity 

(40 CFR 1508.27). Context includes spatial, temporal, and ecological parameters, such as the size of the 

affected area, the duration of the effect, and the ability of the resource to recover from the effect. 

Intensity describes the severity of the effect. Significance can sometimes be defined quantitatively, as 

when a measured concentration of a chemical in the environment is compared with a toxicological 

benchmark. More often, significance is described using qualitative measures because data are not 

available to support quantitative analysis. A Finding of No Significant Impact (FONSI) under NEPA 

represents a conclusion that the expected impacts are below a level of significance that would warrant 

preparation of an EIS (40 CFR 1508.13). In the discussion below, Shell provides scientifically defensible 

rationale to support a FONSI for the proposed action. 

4.1 Air Quality

No site-specific air quality data are available for the project area, which is 79 miles (127 km) from the 

nearest shoreline. Attainment status under the Clean Air Act pertains only to state waters; the project 

site is in federal OCS waters and so is unclassified (MMS 2007b, Matthews and Cameron 2010). All 

coastal parishes in Louisiana and counties in Mississippi, Alabama, and Florida are attainment areas under 

the National Ambient Air Quality Standards (NAAQS) for all criteria pollutants (EPA 2011a). The proposed

action would occur in the open Gulf of Mexico, where air quality is expected to be good. 

Winds in the northern Gulf of Mexico are driven by the clockwise circulation around the Bermuda High, 

which creates prevailing winds toward the shore (MMS 2007b). The prevailing winds are affected by 

hurricanes and tropical storms during summer and fall and by extratropical cyclones (cold fronts) during 

winter. During a 12-month period, winds may blow from virtually any direction (MMS 2007b). Potential 

IPFs resulting from routine activities and accidental events are described below.

4.1.1 Impacts of Routine Activities on Air Quality

The projected emissions for the drillship are below exemption levels, as presented in the Air Quality 

Emissions Report (see Initial EP Section 8). Therefore, according to the definitions set forth in 

30 CFR 250.303, drillship emissions will not significantly affect onshore air quality for any of the criteria 

pollutants. No further modeling, analysis, or control measures are required. Shell‘s standard policy is to 

use low-sulfur fuel to minimize impacts from fuel combustion.

The drillship, support vessels, and helicopters will produce air emissions typical of combustion of diesel 

fuel in generators, pumps, and motors. Routine activities will contribute primary air pollutants such as 

suspended PM, SOx, NOx, VOCs, and CO. Offshore emissions of this sort are not considered to adversely 

affect air quality onshore because of the temporary nature of the activity and the distance of the project 
area from shore. Prevailing atmospheric conditions, emission heights, and emission rates further limit the 

impacts to air quality (MMS 2007b). 

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

potential emissions within 186 miles (300 km) of the Breton Wilderness Area, which is designated as a 

Prevention of Significant Deterioration (PSD) Class I air quality area under the Clean Air Act (NPS 2010). 

The lease area is approximately 105 miles (169 km) from the Breton Class I area. Emissions associated 

with the proposed action are low, and Shell does not anticipate any impacts to air quality in the Class I 

area. Shell will comply with any emissions requirements. Routine activities associated with the proposed 

action would not cause violations of any NAAQS or significantly affect air quality.

4.1.2 Impacts of Small Fuel or Chemical Spill on Air Quality

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

proposed action, comparable to those described in recent EISs (MMS 2007b, 2008; BOEM 2011a; NOAA 

2006). Shell‘s standard procedures and personnel training are focused on minimizing the incidence of 

small spills during routine operations such as fuel transfer. If a small spill were to occur, Shell‘s OSRP 

would be implemented to contain and clean up the spill so that impacts would be minor and transitory 

(Initial EP Sections 2j and 9b). No significant impacts to air quality would result because the 

proposed action is far from shore in the open Gulf and a small spill would be cleaned up quickly.

4.1.3 Impacts of a Large Oil Spill on Air Quality

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

the SEA S-7445 (BOEM 2011b). A large spill would cause short-term localized impacts to air quality as 

VOCs evaporated from the slick. Weather conditions at the time of the release would control the 

immediate behavior of the slick, with greater volatilization occurring during warmer weather. Data from 

the DWH event suggest that most of the methane released during a spill would remain in the water 

rather than enter the atmosphere (Yvon-Lewis and others 2011). Shell‘s OSRP describes the type of 

containment that would occur to minimize impacts of a large spill. Under certain conditions, the incident 

commander may determine that in situ burning is the most appropriate response. Typically, in situ

burning generates a visible plume of black smoke and additional emissions of NOx, SOx, CO, PM, and 

greenhouse gases (USCG 2009).

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

79 miles (127 km) from the nearest shoreline. If the spill were not contained quickly, oil could move 

toward the coast and temporarily affect onshore air quality, especially in Plaquemines Parish (Table 4). 

Plumes of concentrated organic aerosols were detected over the Gulf of Mexico downwind from the DWH 

surface slick as the more volatile constituents were volatilized (deGouw and others 2011; Coe 2011). Any 

air quality impacts would be transitory, based on data collected following the DWH event. EPA‘s air 

quality monitoring data indicate that the DWH spill and associated in situ burning did not result in any 

long-term impacts to air quality (EPA 2011b). Based on the WCD calculation, a large oil spill under the 

proposed action would not exceed the volume of the DWH spill. The proposed action would not cause 

any long-term significant impacts to air quality. No long-term reduction in air quality resulting from the 

proposed action would affect either humans or wildlife. 

A large oil spill is an extremely rare event, made even more unlikely by the enhanced prevention and 

containment protocols developed since the DWH event (described in Initial EP Section 2j and Shell‘s 

OSRP). Were a large spill to occur, Shell would immediately implement its OSRP to mitigate and reduce 

the potential impacts. No significant long-term impacts to air quality, measured as concentrations of 

contaminants exceeding NAAQSs, are expected to result from a large spill because of Shell‘s rigorous 

measures to prevent a spill and the expanded capability through the MWCC to respond to an unplanned 

release.
4.2 Water Quality

Deep waters of the northern Gulf of Mexico are characterized by relatively uniform temperature, salinity, 

and oxygen, and very low levels of contaminants (Kennicutt 2000). The lease area where the proposed 

action would occur has no unique water quality features and is expected to conform to the descriptions in 

the Multisale and Supplemental EISs (MMS 2007b, 2008). The entire northern Gulf of Mexico, especially 

off the coast of Louisiana, is known to contain areas where oil, gas, and brine naturally seep into 

sediments and enter the water column. Oil enters the Gulf of Mexico from these natural seeps as well as 

from the Mississippi River (NRC 2003). 

Water quality at the lease site may have been temporarily affected by the DWH event. The proposed 

project area is only 52 miles (83 km) southeast of the Macondo well site, within the area that was 

covered by the surface slick in May 2010 (ESRI 2010). Subsequent weathering of oil and mixing of Gulf 

waters is expected to have eliminated any residual effects on water quality at the lease site. According to 

analyses conducted by OSAT, polycyclic aromatic hydrocarbons (PAH) concentrations in water and 

sediment samples collected beyond a 1.8-mile (3-km) radius of the Macondo wellsite had dropped below 

the chronic toxicological benchmarks by August 2010 (OSAT 2010). Weathering and dispersion of 

residual oil since that time would have further reduced the concentrations of PAHs in overlying water. 

Available data indicate that water quality in the proposed project area has recovered from any transient 

effects of the DWH event. 

The IPFs potentially affecting water quality include NPDES-permitted effluent discharges, an accidental 

small fuel or chemical spill, and a large oil spill.

4.2.1 Impacts of Routine Activities on Offshore Water Quality

The proposed action will comply with all limitations and regulations in NPDES general permit GMG 

290000. Permitted discharges would have only temporary, localized impacts on offshore water quality, 

and no impact on coastal water quality. Permitted discharges include treated SBM cuttings, sanitary and 

domestic wastes, deck drainage, desalination unit brine and uncontaminated cooling water, fire water, 

and ballast water (outlined in Initial EP Table 7a). 

Discharge of treated SBM would temporarily increase turbidity in the immediate vicinity of the drillship 

and up to several kilometers from the discharge point (NRC 1983, Neff 1987; Netto 2009, 2010). Apart 

from the transient increase in suspended solids, no other impacts to water quality are expected. The 

small amount of SBM retained on discharged cuttings remains bound to the cuttings as the cuttings sink 

to the seafloor (Neff and others 2000). Discharge of treated SBM would not result in long-term 

significant impacts to offshore water quality; the proposed action would not cause water quality in the 

project area to exceed any toxicological benchmarks for marine life.

Minor and temporary impacts to water quality immediately surrounding the project area would result 

from the permitted discharge of treated sanitary and domestic wastes from the drillship and support 

vessels. Discharges from support vessels are permitted by EPA under the NPDES Vessel General Permit 

(VGP) (EPA 2009). 

Deck drainage would not result in any decrease in water quality beyond the immediate vicinity of the 

drillship. The VGP requires collection and treatment of rainwater that falls on the drillship deck and other 

areas where it may be exposed to contaminants (such as chemical storage area). Rain that falls on clean 

areas of the drillship does not require treatment. Effluents generated by deck washings and runoff from 

curbs, gutters, and drains would be treated before discharge. 

The VGP does not require treatment of desalination unit brine and uncontaminated cooling water, fire 

water, or ballast water because these non-toxic effluents would be rapidly diluted and not result in any 

impacts to offshore water quality. In summary, routine, permitted discharges would not cause any 
significant adverse effects to water quality; no toxicological benchmarks for marine life would be 

exceeded. 

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

As outlined in Section 2.2.1, a small fuel or chemical spill is extremely unlikely to cause any significant 

impact to offshore water quality beyond a transient effect on the immediate localized area. Shell‘s 

approach to minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 

9b.

Shell‘s OSRP includes protocols for containing and cleaning up small fuel or chemical spills. The specific 

procedures would vary depending on the product spilled, location (nearshore/offshore), sea state, 

weather, and other immediate conditions. Regardless of the particular cleanup methods, a small spill (3 

bbl) would be quickly contained and recovered, causing no long-term impact on environmental resources. 

Diesel spills are particularly short-lived because diesel floats on the sea surface, where its low molecularweight constituents readily volatilize (NRC 2003; NOAA 2006). Higher weight constituents that remain in

the waters undergo microbial degradation and oxidation, resulting in short chain carbon compounds. If 

the spill occurs near shore, some of the diesel may enter coastal vegetated habitats for a brief time. 

However, microbial degradation would occur in the vegetated areas as well, and impacts would be 

transient (NOAA 2006). It is expected that small fuel spills will occur predominantly in the open Gulf of 

Mexico where no significant impacts to water quality would result because most fuel transfers occur at 

the drillship rather than near shore. The spill would not impair the ability of offshore waters to support 

marine life. Even if a small spill reached the shore, impacts to fishes would be transient and reversible. A 

spill of 600 bbl of crude oil in Barataria Bay, Louisiana had no long-term effects on species composition or 

community structure of fishes; both of these metrics had returned to baseline condition within one year 

of the spill (Roth and Baltz 2009). 

The MC Block 525 lease area is 79 miles (127 km) from the nearest shoreline (Figure 1). Spill trajectory 

modeling predicts that a large spill in the project area would not reach the shoreline within 10 days of a 

spill (Table 4). A small diesel spill would be fully volatilized or degraded within 10 days, reducing the risk 

of shoreline contact to zero (NOAA 2006). Even larger fuel spills (up to 1,000 bbl) are not expected to 

remain visible on the surface of the water long enough to cause significant impacts to coastal lands (MMS 

2007b). Quantitative spatial modeling that incorporates degradation and breakdown of the fuel as well 

as actual paths of historical spills concluded that coastal habitats are not at substantial risk of oiling by 

spills smaller than 1,000 bbl (MMS 2007b).

Although it is possible that other chemicals would be spilled, the probabilities are exceedingly small. MMS 

evaluated small spills of fuel and other chemicals and concluded that chemical spills are not likely to 

cause significant impacts to environmental resources in the OCS (MMS 2008; BOEM 2011a); no 

toxicological benchmarks would be exceeded. More than 20 chemicals typically used in deepwater OCS 

activities were evaluated for toxicity to marine organisms. Most of the chemicals posed no risk to 

environmental resources in the volumes used in deepwater projects. Only zinc bromide and ammonium 

chloride could cause impacts to marine resources (Boehm and others 2001). Neither zinc bromide nor 

ammonium chloride would be used in the proposed action. Small fuel or oil spills would have no 

significant impact on water quality.

4.2.3 Impacts of a Large Oil Spill on Offshore Water Quality

A blowout resulting in a large oil spill is an exceedingly unlikely event, as described in Section 2.2.2 and 

in the Multisale EISs (MMS 2007b, 2008; BOEM 2011a). Shell has certified in its OSRP that it is prepared 

to respond to a spill substantially larger than any spill that could result from the proposed action (see 

Shell‘s OSRP). Following the guidance provided in NTL 2010-N06, Shell calculated that 271,000 bbl could 

be discharged during the first day, with a 30-day average of 233,000 BOPD. During the 157 days it 

would take to drill a relief well, a total volume of 11.4 million barrels of oil could be discharged. 

Calculations supporting these volumes are in Initial EP Section 2j.
In the unlikely event that a large spill were to occur under the proposed action, oceanographic conditions 

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

described in Section 2.2.2 and Table 4. Potential impacts of a large spill were evaluated in the Multisale 

and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a). A large spill would produce an initial slick on 

the water surface, which would immediately begin to disperse and weather. 

Once oil is released from the well, it mixes with seawater and separates into fractions that have different 

physical and chemical characteristics that influence how they behave. Storms or other disturbances 

increase the rate of dispersion of the surface slick and enhance the dissolution of the lowmolecular‐ weight aliphatic and aromatic hydrocarbons into the water column (OSAT-2 2011, NRC 2003). 

The volume of spilled crude oil decreases within a few days of a spill. Only 25 percent of the original 

volume of spilled light crude oil would remain after a few days (up to 60 percent of a medium crude oil

spill) as the lower molecular weight benzene, toluene, ethyl benzene, and xylenes are lost (OSAT-2 

2011.)

When subsea dispersants are applied to the oil during a release, the oil may move laterally beneath the 

surface of the water rather than rising to the surface as expected (Camilli and others 2010, Hazen and 

others 2010, Joint Analysis Group 2010a, b, c). The dispersants themselves may affect offshore water 

quality for some time after the spill. After the DWH event, oil and dispersants were detected at 3,280 to 

3,937 feet (1,000 to 1,200 m) as far as 186 miles (300 km) from the wellsite (Kujawinski and others 

2011). Over time, water quality would return to pre-spill conditions as the remaining oil and dispersant 

were degraded and diluted by Gulf waters (MMS 2007b; BOEM 2011a). 

A large oil spill may include a release of gaseous hydrocarbons that could temporarily impair offshore 

water quality. The proposed action is in an area where the concentration of H2S is unknown. The 

release and subsequent metabolization of methane could cause a short-term minor decrease in dissolved 

oxygen concentrations in the area. Transient depressions in dissolved oxygen concentrations may follow 

an oil spill as microbes degrade the oil, but no long-term hypoxia (defined as less than 2.0 milligrams 

[mg] per liter [L]) is expected to occur (Joye and others 2011, Kessler and others 2011, OSAT 2010). 

Depressed dissolved oxygen concentrations near the Macondo wellhead had returned to pre-spill levels 

by October 2010, 6 months after the release (OSAT 2010).

The lease area is 79 miles (127 km) from the nearest shoreline, reducing the likelihood that coastal water 

quality impacts would result from a large oil spill. The OSRA model predicts that the most likely 

nearshore water quality impacts would occur near Plaquemines Parish, Louisiana (Table 4). Shell‘s OSRP 

focuses on rapid containment of a spill so that coastal waters would not be affected, as described in 

Initial EP Section 2j and 9b. The combined effort of prevention, containment, and rapid cleanup 

detailed in Shell‘s OSRP make it extremely unlikely that a large spill would cause any long-term significant 

impacts to water quality.

4.3 Lower Trophic Level Organisms 

By far the most abundant organisms in the open waters of the Gulf of Mexico are phytoplankton and 

zooplankton. The plankton community consists of both permanent members and transient larval forms of 

fishes and invertebrates (Johnson and Allen 2005). Plankton and marine invertebrates in the open waters 

of the Gulf of Mexico are the basis of the food web that supports fish, birds, sea turtles, and marine 

mammals and provides recreation and economic benefits to people. The composition of the planktonic 

community in any given location and depth changes over time in response to physical factors such as 

wind, currents, turbidity, nutrient availability, and light (Hernandez and others 2010). Ecological 

processes such as predation and competition also influence the abundance and distribution of various 

species. Lower trophic level communities are characterized by mixed species assemblages of 

phytoplankton, zooplankton, and ichthyoplankton, as well as benthic and pelagic invertebrates. These 

organisms are predominately moved passively within water masses, although some have limited 

swimming abilities. 
The tiny size, wide distribution, and overall abundance of most lower trophic level organisms in the open 

Gulf of Mexico affords these species protection from small, localized impacts. None of the routine IPFs 

would cause population-level effects. Entrainment of plankton life forms by large capacity water intakes 

has historically been a concern; however, modern intake structures are designed to allow mobile plankton 

to escape and to limit the entrainment of smaller life forms. The Noble Globetrotter is a new drillship that 

would meet the BTA requirements of minimizing entrainment and impingement to reduce impacts to nonsignificant levels. 

The only accidental IPF that could potentially affect lower trophic levels is a large oil spill, which could 

cause direct mortality by smothering the organisms. However, lower trophic organisms tend to be 

ubiquitous across the well-mixed waters of the northern Gulf of Mexico, carried long distances by the 

Loop currents. Even a large spill would not have population-level impacts on any species of lower trophic 

level organism. 

4.4 Deepwater benthic communities

Benthic habitats in the northern Gulf of Mexico support both chemosynthetic and nonchemosynthetic 

communities. NTL 2009-G40 requires a description of features or areas that could support high-density 

chemosynthetic communities, deepwater corals, or other associated high-density hard-bottom 

communities in waters deeper than 984 feet (300 m) so that these sensitive biological communities can 

be avoided.

Chemosynthetic Communities

Oil, gas, and brine seeps cover a substantial portion of the Gulf of Mexico, especially on the continental 

margin, and chemosynthetic communities have been discovered in Gulf waters as deep as 10,825 feet 

(3,300 m) (Fisher and others 2007). More seeps have been discovered in the Gulf of Mexico than in all 

other oceans combined; however, less than 1 percent of the deepwater Gulf of Mexico is believed to 

support high-density benthic communities (BOEM 2011c). The Gulf of Mexico also supports deepwater 

coral communities that become established on the carbonate substrates created by chemosynthetic 

communities (MacDonald 2001; Brooke and Schroeder 2007, Cordes and others 2008). Seismic studies 

show that hard bottom areas occur where authigenic carbonates were generated by the seepage process, 

mostly along the margins of intraslope basins (Fisher and others 2007; Brooks and others 2009).

Surveys did not document any features that could support high-density deepwater chemosynthetic 

communities within 2,000 feet (610 m) of the proposed wellsites (C&C Technologies 2009). The list of 

known high density deepwater benthic communities provided as a reference to NTL 2009-G40 does not 

include any locations as far east as the proposed project area (longitude -87.96) or any communities 

within MC 525. Nor is MC 525 mentioned in recent summaries of important deepwater benthic related 

communities in the northern Gulf of Mexico (Fisher and others 2007; Cordes and others 2008, 2009; 

Brooks and others 2009). 

As described in Initial EP Section 6a, the proposed well locations are in water ranging from 7,450 to 

7,600 feet (2,270 to 2,316 m). MC 525 is in the extreme northern section of deepwater Grid 17, where 

remotely operated vehicle (ROV) coverage of the seafloor is considered inadequate to characterize the 

area (BOEM 2011f). Based on general surveys of the MC area, the seafloor is expected to be 

predominately softbottom (Rowe and Kennicutt 2009).

Nonchemosynthetic Communities

The Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology study provides site-specific 

data on benthic habitats, communities, and species at more than 40 sampling locations (Wei 2006, Rowe 
and Kennicutt, 2009). One sample location (S37) located in the vicinity of the proposed well site in a 

comparable water depth 7831 feet (2,387 m) is considered representative of the project area. Sediment 

at Station S37 was more than 80 percent silt and clay; the remainder was sand. The benthic community 

was typical of a softbottom basin. No hardbottom substrate was reported at this location (Rowe and 

Kennicutt 2009). 

In general, benthic marine softbottom communities are described in terms of the mean size of organisms, 

defined by the type of sampling gear used to collect them. The smallest organisms are the microbiota, 

including bacteria, protists, and benthic foraminiferans. Many of the bacteria are capable of consuming 

hydrocarbons (Atlas and Hazen 2011). Bacteria and other microbiota form the basis of the marine food 

web in the lease area and also function in cycling organic carbon (Rowe and Kennicutt 2009) (see Section 

2.2.2). 

The meiofauna are defined as organisms retained by a 63-micron (0.063-millimeter [mm]) sieve. The 

density of meiofauna at Station S37 was 219,179 individuals per square meter (m2) of sediment. Most of 

the biomass was composed of nematodes (soft worms similar to pinworms), as is typical throughout the 

Gulf of Mexico. Macrofauna, organisms that are retained by a 300-micron (0.3-mm) sieve, were 

dominated by polychaetes (bristly marine worms) at Station S37, consistent with most softbottom 

deepwater marine habitats. Other macrofauna at Station S37 included amphipods, tanaids, bivalves, and 

isopods. Megafauna are organisms visible to the unaided eye, at least 100 mm wide. At Station S37, 

small sponges (Family Ancorinidae) and the orange brittle star (Ophiocrates heros) were dominant 

components of the megafauna (Wei 2006, Rowe and Kennicutt 2009). 

Surveys of the northern Gulf of Mexico demonstrated that benthic organisms occur in four depthdependent faunal zones (1 through 4, shallow to deep). The proposed project area is in Zone 3E, which 

consists of stations in the west flank of the lower Mississippi Fan, the lower Mississippi Canyon, the lower 

De Soto Canyon (S37), the lower West Florida Terrace, the deep Mississippi Fan, and one station at the 

base of the Sigsbee Escarpment ranging in depth from 7,200 to 10,800 feet (2,200 to 3,300 m). 

Dominant macrofauna of faunal Zone 3E included the polychaetes (Paraonella monilaris and Tharyx 

marioni), two bivalves (Heterodonta spp.), and an isopod (Macrostylis sp.) (Wei 2006).

Deepwater corals (also called coldwater corals) occur in the Gulf of Mexico, although not in the lease 

area. Most deepwater corals do not form reefs like those in tropical waters. Instead, they form patches of 

corals, especially Lophelia pertusa, that create habitat for other organisms (Brooke and Schroeder 2007). 

Deepwater reefs support biologically rich and diverse communities of crustaceans, mollusks, 

echinoderms, polychaete worms, sponges, and other larger animals. Deepwater corals also provide 

crucial habitat and reproductive grounds for commercially important fisheries. The only IPF that could 

adversely affect deepwater corals is a large oil spill because of the distance of the project area from these 

communities. 

Routine IPFs potentially affecting benthic communities include activities resulting in effluent discharges of 

drilling mud and cuttings and a large oil spill. A small fuel or chemical spill is not considered an IPF 

because the spill would not contact benthic communities more than 7,546 feet (2,300 m) below the sea 

surface (see Section 2.2.1). The drillship itself is not considered an IPF because it does not require 

anchors and will not contact the seafloor except at the location of the wellbore, which is described in 

Section 2.1.2.

4.4.1 Impacts of Routine Activities on Deepwater Benthic Communities

Routine activities associated with the proposed action would have no impact on chemosynthetic 

communities or deepwater coral because the project area is not in proximity to any such communities 

(Initial EP Section 7). Potential effects on common nonchemosynthetic communities are discussed 

below. 
Drillships such as the Noble Globetrotter do not use anchors for holding or stabilization during drilling 

operations. Positioning of the wellbore and BOP will cause minimal disturbance to benthic softbottom 

communities in the immediate area where the wellbore penetrates the substrate, where mud and drill 

cuttings will be deposited. During installation of the initial well intervals before the marine riser is set, 

cuttings and seawater-based ―spud mud‖ will be discharged to the seafloor. Some excess cement slurry 

will be released at the seafloor when casings are installed on the riserless portion of the well. The 

chemical constituents of cement slurry are not considered particularly toxic to marine life (Boehm and 

others 2001); however, the cement and mud can physically smother or bury benthic organisms within 

tens of meters around the wellbore (Neff and others 2005; Hughes and others 2010). The disturbed area 

of softbottom sediments would be recolonized by larvae recruited from the overlying water or adjacent 

areas, but recovery may take several years (Hughes and others 2010). Species composition may shift 

during the recovery period as more species more tolerant of residual hydrocarbons return first, followed 

by other species only after the sediment returns to pre-drilling conditions (Netto and others 2010). 

In addition to cement slurries and mud, treated SBM cuttings discharged from the drillship and may 

adversely affect softbottom communities near the wellbore. Although the cuttings may physically harm 

benthic organisms, they do not generally pose a risk of toxicity (Rowe and Kennicutt 2009; Netto and 

others 2009). Sediments in areas of particularly dense drilling activity, such as the Mississippi Canyon, 

may contain elevated concentrations of barium compared with background sediments; however, even the 

highest concentrations measured around drilling sites were found not to be toxic to marine organisms 

(Rowe and Kennicutt 2009). The treated SBM cuttings do not persist indefinitely in the environment, but 

instead are gradually integrated into the benthic habitat as the base synthetic fluid is transformed to its 

elemental components by microbes (Hughes and others 2010). Once drilling stops, larval recruitment 

from the overlying water and adjacent seafloor will return the area to its pre-drilling condition (Netto and 

others 2009).

The spatial footprint of drilling discharges is typically considered to be limited to a radius of about 

1,640 feet (500 m) around each wellsite. The affected footprint would be 970 acres (393 hectares). 

Routine activities associated with the proposed action would not significantly affect softbottom benthic 

communities in the vicinity because no rare or unique softbottom communities occur within MC 525 (Wei 

2006, Rowe and Kennicutt 2009). The minor impact to a limited number of individuals is not considered 

to threaten the long-term sustainability or productivity of native softbottom benthic communities. This 

conclusion is consistent with the analyses developed in the regional Multisale and Supplemental EISs 

(MMS 2007b, 2008; BOEM 2011a). 

4.4.2 Impacts of a Large Oil Spill on Deepwater Benthic Communities

A blowout would resuspend and disperse sediments within a 984-foot (300-m) radius of the well site and 

have a direct adverse effect on benthic communities within that area (MMS 2007b). Although largergrained sediments (sands) would probably settle quickly within 1,312 feet (400 m) of the blowout site, 

finer silts and clays could remain in the water column for weeks and would be transported kilometers 

from their original location. A large volume of suspended sediment would likely result from a blowout 

because the project area substrate is more than 80 percent silts and clays (Rowe and Kennicutt 2009). 

No chemosynthetic, deepwater coral, or other high-density hardbottom communities occur near the well 

sites. The direct physical blowout event would not have any direct impact on high-density benthic 

communities. 

Before the DWH event, deepwater benthic communities in Gulf waters were thought to be relatively 

protected from large oil spills because oil naturally rises to the sea surface (MMS 2007a, 2008). 

However, it was demonstrated during the DWH response that application of subsea dispersants changed 

the fate and transport of the oil (Joint Analysis Group 2010c). Subsurface plumes in water more than 

3,600 feet (1,100 m) deep were observed more than 20 miles (32 km) from the point of release about a 

month after the event (Camilli and others 2010). About 8 miles (13 km) from the DWH wellhead, a welldefined plume of oil between 3,280 and 13,123 feet (1,000 and 1,400 m) deep contained concentrations 
of PAHs toxic to marine life (Diercks and others 2010). Others reported that chemical components of 

subsea dispersants applied during the DWH event were detected up to 186 miles (300 km) from the 

wellsite in water below 3,280 to 3,937 feet (1,000 to 1,200 m) more than 2 months after the spill 

(Kujawinski and others 2011). 

EPA permitted the use of subsea dispersants because the concentrations were believed to pose little risk 

to marine organisms. However, data on the use of subsea dispersants are limited, and it cannot be 

determined at this time whether dispersants would be permitted as part of the response to a blowout 

under the proposed action. This analysis assumed that dispersants could be used, and that benthic 

communities could be exposed to a subsurface plume of oil beyond the 984-foot (300-m) radius affected 

by the physical blowout (MMS 2007a, 2008). 

The impact of a large oil spill on benthic communities is considered temporary and not significant 

because no unique or rare high-density benthic communities occur within the vicinity of the proposed 

action. Available data indicate that the affected area would be recolonized by common benthic 

organisms over a period of months to years (NRC 2003; BOEM 2011a; Netto and others 2009, 2010).

Chemosynthetic Communities

A large oil spill has the potential to affect chemosynthetic communities some distance from the blowout 

site, as described above. Although chemosynthetic organisms can tolerate, and may even require, 

certain concentrations of hydrocarbons, it does not follow that they can withstand concentrations above 

their biological threshold. Natural seeps vary in both chemical constituents and flow rate, and a 

chemosynthetic community may be tightly coupled to the particular conditions that prevail at its seep. 

The chemosynthetic community goes through successional stages as the flux of hydrocarbons begins, 

peaks, and then declines over time. A sudden plume of free product in the water column in no way 

represents a natural occurrence for a chemosynthetic community. 

Chemosynthetic organisms grow slowly, and have limited ability to avoid or recover from exposure to oil 

in the water column. Impacts of a large spill to chemosynthetic communities include mortality, but also 

effects such as reduced growth, tissue damage, and impaired reproduction (BOEM 2011b). Loss or injury 

of the chemosynthetic host organisms can cause a cascade of impacts to other organisms associated with 

the seep. Mobile organisms such as large crabs and echinoderms may be physiologically less able to 

tolerate elevated concentrations of hydrocarbons (BOEM 2011b).

Severely damaged seep habitats could be recolonized by planktonic tubeworm larvae recruited from as 

far as 350 miles (560 km) away (Cordes and others 2007; 2009). Some communities undergo a phase 

shift to a different type of community once the area becomes suitable for recolonization because the 

seeps themselves do not persist indefinitely (Fisher and others 2007). If oil or dispersants were to contact 

chemosynthetic communities, adverse effects such as reduced growth, impaired reproduction, or 

mortality could occur (Hamdan and Fulmer 2011; BOEM 2011a). The long-term impact on 

chemosynthetic communities from a large oil spill is difficult to predict because large spills are so rare and 

chemosynthetic communities are so sparsely distributed and diverse.
Nonchemosynthetic Communities 

Data from the DWH event demonstrated the potential for a large oil spill to adversely affect 

nonchemosynthetic communities, particularly deepwater corals (BOEM 2010a). At a deepwater coral site 

4,600 ft (1,400 m) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead, 

government and academic researchers observed large populations of injured and dead corals that were 

sloughing tissue and other soft and stony corals covered by a brown substance. Although circumstantial 

evidence points to the DWH event as the causative agent of the injured corals, laboratory analyses have 

not yet confirmed the identity of the brown substance. 

Oil spills can impair deepwater corals by degrading hardbottom habitat, altering the assemblage of 

species in an area, and reducing live coral coverage. Any disturbance of coral can lead to secondary 

losses of associated species because deepwater coral communities provide complex biogenic structure 

that supports a range of other species. Effects on deepwater corals could impair their ability to recover 

from other disturbances, including increases in sea temperature, acidification, and coral diseases (MMS 

2007b, BOEM 2011a).

Chemosynthetic communities, deepwater corals, and other live hardbottom communities could be 

adversely affected by a large oil spill under the proposed action. However, a large spill is extremely 

unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial 

EP Section 2j). In the event that a blowout did occur, Shell‘s spill response measures would minimize 

the impacts by quickly containing and recovering the oil. Initial EP Sections 2j and 9b provide detail 

on Shell‘s spill response plan. Therefore, no significant spill impacts on deepwater benthic communities 

are expected. 

Other Sensitive Benthic Areas

In the Gulf of Mexico Large Marine Ecosystem, a zone of tuft coral provides hardbottom habitat in water 

1,640 ft (500 m) deep (Reed and others 2006). The west Florida shelf is a broad carbonate platform 

extending from DeSoto Canyon in the north to the western Straits of Florida, an area of about 30,115 mi2

(78,000 km2). At the edge of the Florida Platform, reef and limestone outcrops provide deepwater 

hardbottom habitat (Hourigan 2009). Deepwater banks and associated hardbottom communities occur in 

the western and central Gulf of Mexico (Hourigan 2009). Tuft coral thickets occur on Viosca Knoll off the 

coast of Alabama and in DeSoto and Green Canyons (Reed and others 2006). In the Gulf of Mexico, 

between the Mississippi Canyon and the DeSoto Canyon, are two bands of carbonate mounds called the 

Pinnacle Trend, which offer substantial live hardbottom habitat in an otherwise softbottom area (MMS 

2007b). 

The proposed project area is not within or near any designated topographic feature or a no-activity zone 

as identified in NTL 2009-G39. The nearest topographic feature is Sackett Bank in the West Delta South 

area (Blocks 147-148). The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. 

As defined by NTL 2009-G39, the nearest pinnacle trend blocks are in the Viosca Knolls area north of the 

project area. The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which applies to 

Eastern Gulf of Mexico Planning Area leases in water depths of 328 feet (100 m) or less.

Neither routine activities nor accidents would adversely affect designated topographic features, pinnacles, 

or other live bottoms because of the distance of these features from the lease area. A small fuel or 

chemical spill would float or dissipate quickly before it could reach these areas of topographic relief 

(NOAA 2006). A large oil spill could be transported up onto the continental shelf where these features 

occur, but this event is considered unlikely (Nowlin and others 2001). 
4.5 Fish, Fisheries, and Essential Fish Habitat

Potential impacts of oil and gas activities on fish, fisheries, and essential fish habitat (EFH) were analyzed 

in the Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a) and the site-specific SEA S7445 for leases near the project area (BOEM 2011b); the background information and analyses in those 

documents are incorporated by reference into this EIA. The proposed action does not include any unique 

or unusual IPFs that would warrant a separate analysis, and no significant impact on fish, fisheries, or 

EFH is expected to result from routine activities or small fuel or chemical spills. Shell would comply with 

NTL 2007-G03 to minimize the potential for marine debris-related impacts on fishes. Implementation of 

Shell‘s OSRP would reduce the impact of small fuel or chemical spills to fishes to insignificant levels. 

Additional analysis of potential impact of a large oil spill on fish, fisheries, and EFH is presented for the 

Gulf sturgeon and its critical habitat, which are protected under the ESA (Section 4.5.2); other fishes and 

EFH are discussed in Section 4.5.3.

4.5.1 Gulf Sturgeon

The federally threatened Gulf sturgeon (Acipenser oxyrinchus desotoi) inhabits major rivers and coastal 

waters from the Mississippi River east to the Suwannee River, Florida. A description of the species is 

given in the Multisale EIS (MMS 2007b) and summarized briefly here. The Gulf sturgeon lives up to 42 

years and is a slowly maturing species. Females reach maturity at 8 to 17 years and males at 7 to 21 

years (FWS and NMFS 2009; NMFS 2010a). The Gulf sturgeon is anadromous, spawning in freshwater 

rivers and feeding in estuarine and marine waters of the Gulf of Mexico (FWS and Gulf States Marine 

Fisheries Commission 1995).

Once the Gulf sturgeon leaves the freshwater habitat, it typically inhabits estuaries and nearshore bays in 

water less than 35 feet (10 m) deep (Ross and others 2009). Barrier island inlets provide important 

winter foraging grounds where Gulf sturgeon originating from different rivers congregate (Sulak and 

others 2009). During much of the winter, juvenile Gulf sturgeon exhibit a preference for estuaries less 

than 7 feet (2 m) deep, venturing into deeper offshore waters only for short periods during cold weather 

(Sulak and others 2009). The adult Gulf sturgeon prefers high sand content and clean sand substrata 

(Fox and others 2000; Harris and others 2005; Ross and others 2009). 

Distribution of the Gulf sturgeon in the marine environment is likely influenced by availability of preferred 

prey (Ross and others 2009). Feeding habits vary by life stage, but in general the Gulf sturgeon is an 

opportunistic feeder in estuarine and marine habitats, taking a wide variety of benthic invertebrates such 

as amphipods, polychaetes, gastropods, shrimp, crabs, isopods, mollusks, and crustaceans (FWS and Gulf 

States Marine Fisheries Commission 1995; FWS and NMFS 2009). In the Mississippi Sound area, the Gulf 

sturgeon was reported to take sand dollars and annelids as well (Ross and others 2009).

In a 5-year review published in 2009, the NMFS and FWS considered the status of the Gulf sturgeon as 

stable, indicating that 26 to 50 percent of recovery objectives had been achieved (FWS and NMFS 2009).

4.5.2 Impacts of a Large Oil Spill on Gulf Sturgeon

The potential for a large oil spill to adversely affect the Gulf sturgeon was analyzed in the Multisale and 

Supplemental EISs (MMS 2007b, 2008), by the NMFS in its Biological Opinion for the Five-Year Oil and 

Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico (NMFS 2007), and 

in the site-specific SEA S-7445 for a nearby lease (BOEM 2011b). The proposed action would be 

consistent with the actions evaluated in those documents, which are incorporated by reference. 

The nearest Gulf sturgeon critical habitat to the lease area is about 121 miles (195 km). Spilled oil would 

not contact Gulf sturgeon critical habitat within 30 days, based on OSRA modeling (Table 4).

If spilled oil reached an area where sturgeon occurred, a sturgeon could be exposed to oil through direct 

ingestion of water, sediment, or prey; and by absorption of dissolved petroleum products through the 
gills. Subadult and adult Gulf sturgeon feeding in coastal waters would be most vulnerable to a marine 

oil spill from September through April (FWS and NMFS 2009). During the rest of the year, they are in 

upriver areas beyond the reach of an offshore oil spill. 

4.5.3 Impacts of Routine Activities on Fishes 

Fish resources in the northern Gulf of Mexico range from tiny ichthyoplankton to the 18-meter-long whale 

shark (Rhincodon typus) (McEachran and Fechhelm 1998). Although the coastal waters of the Central 

Gulf of Mexico are species-rich, both diversity and abundance of fishes drops off as water depth 

increases. Between 4,921 feet and 9,842 feet (1,500 m and 3,000 m), only 32 benthic or demersal 

species in nine families were collected during an intensive trawl survey (Rowe and Kennicutt 2009). 

Fishes are expected to be relatively scarce in the cold deep waters of the project area, dominated by 

various species of eels (McEachran and Fechhelm 1998). 

Highly migratory pelagic species such as tuna and billfishes may transit through the surface waters near 

the project site, but are not considered residents of the area. The most abundant component of the fish 

community in open waters near the drillship would be ichthyoplankton, composed of pelagic eggs and 

larvae of numerous species. Buoyant eggs and larvae remain in the plankton from 10 to 100 days, 

depending on the species (MMS 2007b).

No studies of the reactions of fishes to routine exploration activities in the OCS have been conducted, but 

the published scientific literature can be extrapolated to support an impact assessment of the proposed 

action, as described below. 

4.5.3.1 Impacts of Drillship and Support Vessels on Fishes

The drillship and support vessels could affect fishes by serving as a FAD, producing noise and light, and 

physically colliding with fish in the water. Each of these potential IPFs is discussed below. 

Fish Aggregating Device. Fixed oil and gas platforms are known to act as FADs, which are typically 

defined as floating objects moored at specific locations in the ocean to attract pelagic fishes. Virtually 

any floating object in open water can serve as a FAD. Commercial, recreational, and artisanal fishers 

throughout the world purposefully deploy FADs to draw pelagic fish to targeted capture areas (Fisheries 

and Aquaculture 2010). It is debatable whether these devices actually cause fish to aggregate or only 

attract fish. Ideally, FADs function as floating reefs in the sense that they provide clean attachment 

locations for algae and invertebrates, which then provide forage, shelter, and structure for mobile 

organisms. 

The drillship would not create complex habitat in the same way as a fixed platform because the drillship 

is designed not to accumulate encrusting organisms on its hull. However, as a large floating object, it 

may serve as a temporary aggregating device for mobile pelagic fishes. The commercial fishing interests 

that harvest tuna from the Gulf of Mexico would not set their lines beneath the drillship, and so tuna and 

other pelagic fishes that are attracted to the drillship would be temporarily protected from capture. The 

physical presence of the drillship would have a minor temporary beneficial effect on pelagic fishes such as 

tuna because it creates a temporary no-take zone that would protect some individuals from fishing 

pressure. 

Sound. The drillship and support vessels will generate sounds that could be perceived by marine fishes. 

All fish have two sensory systems that are used to detect sound in the water: the inner ear, which 

functions very much like the inner ear found in other vertebrates, and the lateral line, which consists of a 

series of receptors along the body of the fish (Popper 2008). The inner ear generally detects higher 

frequency sounds while the lateral line detects water motion at low frequencies (below a few hundred 
Hz). It is difficult to discern the impacts of sound alone because vessels tend to produce sound and 

movement at the same time. 

The physiological responses of marine fishes to vessel movements (Brown and Murphy 2010) and 

underwater noise (Popper 2003; Codarin and others 2009; Slabbekoorn and others 2010; Wright and 

others 2010) have been investigated for only a limited number of marine fishes (Popper and Hastings 

2009a,b). Underwater sounds such as engine noise generated from all vessel types have been 

demonstrated to elicit various responses in such fishes as Pacific herring (Clupea pallasii), Atlantic cod 

(Gadus morhua), haddock (Melanogrammus aeglefinus), and sea bass, as described by Buscaino and 

others (2010), Popper (2003) and Popper and Hastings (2009a, b). The physiological structure of hearing 

in fishes results in different responses to underwater human-made sounds, compared with marine 

mammals (Popper and others 2007); in most cases, human-made sound is not expected to affect marine 

fishes at all (Kane and others 2010). Sounds associated with the proposed action would have no 

significant impact on fishes,

Light. Artificial lighting associated with fixed oil and gas platforms is known to attract fishes, especially 

larval and juvenile stages of phototactic species (Lindquist and others 2005; Keenan 2007). Although no 

specific studies of similar effects of lighting on drillships have been published, it is reasonable to assume 

that fishes would react comparably. The increased lighting associated with the proposed action may alter 

the behavior of individual fish in the vicinity of the drillship. This temporary change in the behaior of 

individual fish is not expected to have any population-level consequences or to affect the overall health of 

fish stocks. Artificial lighting would cause no significant impact to fishes.

4.5.3.2 Impacts of Water Intake on Fishes

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

water and once-through, non-contact cooling of machinery on the drilling rig. Cooling water intakes can 

impinge or entrain pelagic organisms, leading to injury or mortality. Under Section 316(b) of the Clean 

Water Act, cooling water intakes must use BTA to minimize impingement and entrainment of organisms. 

EPA recently expanded the Section 316(b) regulations to include ―new, non-fixed‖ facilities such as the 

Noble Globetrotter (implemented via EPA NPDES General Permit GMG 290000). The Noble Globetrotter

will be in full compliance with the BTA requirements specified in the NPDES permit. No significant impact 

to ichthyoplankton or larger pelagic organisms would occur as a result of cooling water intake. 

4.5.3.3 Impacts of Permitted Effluent on Fishes

Effluent discharges for the proposed action would be permitted under EPA NPDES General Permit 

No. GMG 290000 (see Initial EP Section 7). Effluents would include water-based drilling mud and 

cuttings, excess cement slurry, SBM, water-based blowout prevention fluid, treated bilge water, treated 

chemical product waste, non-contact cooling water, treated sanitary and domestic wastes, deck drainage, 

desalination unit brine, uncontaminated fire water, and ballast water.

Effluents discharged at the water surface, including treated SBM cuttings, would quickly become diluted 

by the receiving waters and not cause any significant impacts to fishes. Cuttings and excess cement 

slurry released at the sea floor would increase turbidity in only a localized area where few fishes are 

expected to occur.

4.5.4 Impacts of a Small Fuel Spill on Fishes

The Multisale and Supplemental EISs concluded that a small fuel or chemical spills would not significantly 

affect fishes in the deep Gulf of Mexico (MMS 2007b, 2008; BOEM 2011a). The proposed action does not 

include any unique activities that would change the conclusions of the regional EISs. 

A small fuel spill is the most likely type of spill to result from the proposed action, based on the history of 

exploration and development in the OCS. The programmatic Multisale EIS (MMS 2007b) concluded that a 
minor diesel spill (less than 1,000 bbl) is the most likely type of accident to occur during typical offshore 

activities. The 1,000 bbl is an overestimate of the actual size of most spills in the Central Planning Area, 

which tend to be less than 1 bbl (MMS 2007b). The median size of spills between 1 and 10 bbl is 3 bbl 

(MMS 2007b). Most small spills of this type result from a ruptured hose during fuel transfer.

As outlined in Section 2.2.1, a small fuel or chemical spill is extremely unlikely to cause any significant 

impact to fishes beyond individuals in the immediate localized area (NOAA 2006). Shell‘s approach to 

minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 9b. Shell‘s 

OSRP includes protocols for containing and cleaning up small fuel or chemical spills. The specific 

procedures would vary depending on the product spilled, location (nearshore or offshore), sea state, 

weather, and other immediate conditions. Regardless of the particular cleanup methods, a small spill (3 

bbl) would be quickly contained and recovered, causing no long-term impact to fishes or habitat.

Diesel spills are particularly short-lived because diesel floats on the sea surface, where its low molecularweight constituents readily volatilize (NRC 2003). Higher weight constituents that remain in the waters 

undergo microbial degradation and oxidation, resulting in short chain carbon compounds. If the spill 

occurs near shore, some of the diesel may enter coastal vegetated habitats for a brief time. However, 

microbial degradation would occur in the vegetated areas as well, and impacts would be transient 

(NOAA 2006). It is expected that small fuel spills will occur predominantly in the open Gulf of Mexico, 

where no significant impacts to fishes would result, because most fuel transfers occur at the drillship 

rather than nearshore. 

The proposed action would occur 79 miles (127 km) from the nearest shoreline (Figure 1). Quantitative 

spatial modeling that incorporates degradation and breakdown of the fuel, as well as actual paths of 

historical spills, concluded that fishes are not at significant risk of spills smaller than 1,000 bbl (MMS 

2007b). 

Although it is possible that other chemicals would be spilled, the probabilities are exceedingly small. The 

final Multisale Supplemental EIS (MMS 2008) applied the same evaluation to small spills of fuel and other 

chemicals and concluded that chemical spills were not likely to cause significant impacts to fishes. More 

than 20 chemicals typically used in deepwater OCS activities were evaluated for toxicity to marine 

organisms. None of the chemicals to be used in the proposed action poses a risk to fishes in the volumes 

used in deepwater projects. 

4.5.5 Impacts of a Large Oil Spill on Fishes 

Nearshore assemblages of both adult fishes and ichthyoplankton may be particularly vulnerable to large 

oil spills because of high population densities. Most of the economically and recreationally important 

finfish in the Gulf of Mexico depend at least in part on vegetated coastal habitats in the northern Gulf of 

Mexico, especially west of the Mississippi River (NOAA 2010). Nearshore and estuarine spawning in 

spring and summer produces peaks of ichthyoplankton abundance as waters begin to warm each year 

(Hernandez and others 2010). A large oil spill would have greater effects on a larger number of species 

if it occurred during a time of dense ichthyoplankton aggregations (MMS 2007b). 

Adult fishes are known to actively avoid water contaminated with oil. Most fishes would leave the oiled 

area and not experience prolonged exposure to oil. Limited data available on the long-term effect of the 

DWH event on bluefin tuna indicate that no adverse effects have been realized. Eight tagged adult 

bluefin tuna known to spend time near the Macondo well were tracked for several months after the spill 

and shown to be doing well (Atlantic Bluefin Tuna Status Review Team [ABTSMT] 2011). Fish eggs and

larvae (as well as other plankton) are not able to leave and would likely be adversely affected by the oil. 

Many eggs and larvae occur in the topmost layers of the water and would be exposed to floating oil. Oil 

and ichthyoplankton both tend to accumulate in convergence zones, where the incidence of exposure 

would be increased. 
A large oil spill could significantly affect numerous individual fishes, but would not cause permanent loss 

of any fish populations. The anticipated impacts of the DWH event on marine fishes have not 

materialized to any great extent. Despite the extensive spread of oil in the northern Gulf of Mexico, the 

species composition of nearshore fishes using seagrass nurseries was unaffected (Fodrie and Heck 2011). 

Likewise, the bluefin tuna population, which has been in decline and was directly affected by the DWH 

event, is not expected to experience long-term losses resulting from the spill. Even though up to 20 

percent of its spawning habitat in the Gulf of Mexico was oiled, quantitative models predict that no 

population-level effects will result, partly as a result of natural density-dependent population-level 

processes (ABTSMT 2011). The specific impacts would depend on the time of year, the meteorological 

conditions at the time, the response action, and other variables. 

However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout 

prevention measures (see Initial EP Section 2j) that have been enhanced since the DWH event. In the 

event that a blowout occurred, Shell‘s spill response measures would minimize the impacts by 

immediately containing and recovering the oil. Initial EP Sections 2j and 9b provide detail on Shell‘s 

spill response plan. Therefore, no significant population-level impacts to coastal or offshore fishes would 

result from a large spill.

4.5.6 Impact of Vessel Collisions on Fishes

Collision with vessels is not considered a major threat to most marine fishes (Kappel 2005). Whale sharks 

are an exception because of their large size and basking behavior. Numerous collisions of vessels with 

whale sharks have been recorded (Rowat and others 2007; Stevens 2007). Shell contracts with licensed 

support vessels operators who are responsible for compliance with all requirements regarding transit 

lanes and speed restrictions. Vessel collisions would not significantly affect any fish or fisheries 

resources.

4.5.7 Impacts on Essential Fish Habitat

The Gulf of Mexico Fisheries Management Council (GMFMC) and NMFS have identified waters and 

substrate necessary to fish for spawning, breeding, feeding, and growing to maturity as EFH. The 

GMFMC has developed Fishery Management Plans for several groups of commercially, recreationally, and 

ecologically important organisms, including corals and coral reefs, shrimp, stone crab, spiny lobster, reef 

fishes, coastal migratory pelagic fishes, and red drum. Virtually the entire northern coast of the Gulf of 

Mexico to a depth of about 600 feet (183 m) has been identified as EFH for at least one species. EFH for 

corals and coral reefs includes shallow topographic features in the Central and Western Planning Areas. 

The only EFH in the offshore waters near the lease area is for highly migratory pelagic fishes, including 

sharks, tunas, swordfish, and billfishes (NMFS 2011a). Highly migratory species with EFH in the lease 

area are listed in Table 5.
Table 5. Highly Migratory Fish Species in the Lease Block

Common Name Scientific Name Lifestage at Lease Location

Whale shark Rhincodon typus All

Bigeye thresher shark Alopias superciliosus All

Longfin mako shark Isurus paucus All

Silky shark Carcharhinus falciformes All

Oceanic whitetip shark Carcharhinus longimanus All

Skipjack tuna Katsuwonus pelamis Adults, Spawning Adults, 

Juveniles

Yellowfin tuna Thunnus albacares Adults, Spawning Adults, 

Juveniles

Bluefin tuna Thunnus thynnus Eggs, Larvae

Swordfish Xiphias gladius Juvenile, Larvae

White marlin Tetrapturus albidus Adult, Juvenile

Roundscale spearfish Tetrapturus georgii Adult, Juvenile

Blue marlin Makaira nigricans Adult

Source: NMFS 2009a; 2011a

NMFS also designated an area of about 15,000 square miles (mi2) (300,000 square kilometers [km2]) in 

the Gulf of Mexico as a habitat area of particular concern (HAPC) because the Gulf of Mexico is believed 

to be the primary spawning area for western Atlantic bluefin tuna (ABTSRT 2011). It is thought that 

bluefin tuna larvae rear in the Gulf of Mexico until June, when they migrate to the Atlantic coast (ABTSRT 

2011). HAPCs are defined as areas that are rare, particularly susceptible to human-induced degradation, 

especially ecologically important, or located in an environmentally stressed area. The Magnuson-Stevens 

Act does not provide for any additional protection of HAPCs, but NMFS considers adverse impacts to 

HAPCs more significant than impacts to EFH in general.

Most of the deepwater oil and gas exploration and development sites fall within EFH for highly migratory 

species, particularly for the bluefin tuna. Gulf waters ―west of 86° W and seaward of the 100 m isobath, 

extending from the 100 m isobath to the Exclusive Economic Zone (EEZ)‖ are considered HAPC; the lease 

area is within the HAPC (Figure 3). At least 175 oil and gas platforms currently exist within HAPC for 

bluefin tuna (NMFS 2009a). No other HAPC occurs within the project area (GMFMC 2005) (Figure 3). 

The Multisale EIS found that no routine IPFs associated with exploration activities would significantly 

affect EFH (MMS 2007b). The site-specific SEA S-7445 for a nearby lease corroborated that finding 

(BOEM 2011b). Routine permitted discharges of drilling fluids and cuttings offshore would cause 

transient impacts to water quality, but would not significantly degrade EFH because the discharges would 

be immediately diluted by receiving waters. The proposed action would occur in a localized area for a 

limited duration; no lasting reduction in EFH quality would result. As discussed in Section 4.5.3.1, the 

drillship itself would temporarily add a physical structure to an otherwise featureless area of the open 

Gulf. The drillship may act as a transient FAD while it is at the project site. Drillships and rigs move 

about the Gulf of Mexico intermittently as they are contracted for various projects. They offer familiar 

but movable structures within the larger OCS area and are not expected to represent an adverse 

modification or degradation of any EFH. 

4.5.4.1Impacts of a Small Fuel or Chemical Spill on Essential Fish Habitat 

The Multisale and Supplemental EISs evaluated effects of a small fuel or chemical spill on EFH in the Gulf 

of Mexico and found no significant impact (MMS 2007b, 2008; BOEM 2011a). The proposed action does 

not include any unique activities that would change the conclusions of the regional EISs. Likewise, the 

site-specific SEA S-7445 in a nearby lease block concluded that small spills were unlikely to result in any 
significant impacts to EFH (BOEM 2011b). These documents are incorporated by reference and are 

considered to support the conclusions of this EIA.

As outlined in Section 2.2.1, a small fuel or chemical spill is extremely unlikely to cause any significant 

impact beyond the immediate project area. Shell‘s approach to minimizing the risk of fuel or chemical 

spills is discussed further in the Initial EP Section 9b. Shell‘s OSRP includes protocols for containing 

and cleaning up small fuel or chemical spills. The specific procedures would vary depending on the 

product spilled, location (nearshore or offshore), sea state, weather, and other immediate conditions. 

Regardless of the particular cleanup methods, a small spill (3 bbl) would be quickly contained and 

recovered, causing no long-term impact to EFH. It is possible that a limited area of EFH (or HAPC) could 

be temporarily degraded by a small spill that caused a short-term impact on water quality because the 

project area is within HAPC for the bluefin tuna and other highly migratory pelagic fishes. The project 

area represents a negligible fraction of the 114,793 mi2 (297,312 km2) bluefin tuna HAPC.

A small fuel or chemical spill would dissipate or be collected before it could be transported more than a 

few miles from the lease area (NOAA 2006). No long-term significant impacts to EFH or HAPC would 

result from a small fuel or chemical spill under the proposed action. 

4.5.4.2Impacts of a Large Oil Spill on Essential Fish Habitat

A large oil spill was analyzed in the Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a) 

and site-specific SEA S-7445 in a nearby lease block (BOEM 2011b). The proposed action does not 

include any unique activities that would change the conclusions of the regional EISs or site-specific SEA. 

A large oil spill in the project area would unavoidably affect some EFH because of the vast area of the 

Gulf that is identified as EFH (GMFMC 2005, NMFS 2009a). Impacts to water quality would be temporary 

but potentially widespread, depending on meteorological conditions at the time. A large spill could affect 

the EFH for virtually all managed species in the northern Gulf of Mexico, including shrimp, stone crab, 

spiny lobster, coral and coral reefs, reef fishes, coastal migratory pelagic fishes, and red drum. Any 

impact that decreased the functional quality of the habitat would be considered an impact to EFH 

because EFH is defined in functional terms. Impacts include degraded water quality; decreases in the 

abundance or quality of prey species (phytoplankton, zooplankton, ichthyoplankton, and nekton); oiled 

sediments; and increased physical disturbance (GMFMC 2005). 

A significant impact would occur to the extent that the oil spill caused a reduction in the quantity or 

quality of forage within the EFH for highly migratory species. However, most forage and predator species 

would relocate for a time until the water quality had been restored to pre-spill conditions. Floating 

Sargassum is EFH for the juvenile life stages of a number of managed recreational and commercial 

fishery species, including dolphin fish (Coryphaena hippurus), marlin (Makaira nigricans), sailfish 

(Istiophorus platypterus), cobia (Rachycentron canadum), gray triggerfish (Sufflamen bursa), and 

amberjack (Carangidae). If oil accumulated on the Sargassum mats, the quality of EFH would decline 

temporarily. The increase in human activity associated with a spill response could degrade the quality of 

EFH for a short while, and containment materials could introduce an entanglement risk to highly 

migratory species. However, these effects are considered short-term and not significant. 

The project area is within HAPC for the bluefin tuna. The extent to which a large spill would cause 

significant impacts to the bluefin tuna HAPC depends in part on the timing of the spill (ABTSRT 2011). 

The HAPC is designated based on the importance of the area to bluefin tuna eggs and larvae. If the spill 

occurred early in the summer while eggs and larvae were present, a significant impact to the HAPC (and 

to the species) could occur. Later in the summer (after June), no eggs or larvae are present in the area, 

and the impacts would be less significant. 

If the spilled oil reached coastal EFH, impacts could be longer-lived and more severe. Adult fishes may 

be capable of detoxifying ingested oil to some extent and relocating until conditions improve. Larval and 
juvenile fish are less able to process ingested oil and may suffer toxic effects (BOEM 2011a). In many 

fish species, eggs are the most vulnerable life stage. The probability that oil would reach the more 

sensitive EFH areas is low because a large spill is extremely unlikely to occur. In the event that a 

blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing 

and recovering the oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. 

Therefore, the proposed action is not likely to degrade or adversely modify EFH.

4.6 Sea Turtles (Endangered/Threatened)

All five sea turtle species that occur in the northern Gulf of Mexico are listed as threatened or endangered 

under the ESA (Table 6). All of them could occur near the project area and in coastal waters (Initial 

EP Section 6h). 

Table 6. Federally Listed Sea Turtles in the Northern Gulf of Mexico

Sea Turtles Scientific Name Status

Green turtle Chelonia mydas T, Eb

Hawksbill turtle Eretmochelys imbricata E

Kemp‘s ridley turtle Lepidochelys kempii E

Leatherback turtle Dermochelys coriacea E

Loggerhead turtle Caretta caretta T

b Only the Florida breeding population is endangered. 

4.6.1 Baseline Conditions of Sea Turtles

Juveniles of all Gulf of Mexico sea turtles occur in the general project vicinity, feeding on or near mats of 

floating Sargassum or other material. As adults, only the leatherback and loggerhead sea turtles are 

likely to occur near the drillship. The green sea turtle tends to stay in coastal forging areas, although it 

occurs in convergence zones of the open Gulf of Mexico. The hawksbill sea turtle is most closely 

associated with areas of topographic relief such as coral reefs, ledges, caves, and rocky outcrops, or high 

energy bottoms where upwelling may occur. The Kemp‘s ridley sea turtle is rarely found in water below 

160 feet (49 m).

After they hatch on a high-energy sandy beach, a sea turtle moves among various habitats as it grows. 

Hatchlings and juveniles tend to favor pelagic convergence zones where food is plentiful. As adults, 

green, hawksbill, and loggerhead turtles forage primarily in shallow, benthic habitats. Leatherbacks 

remain in the open Gulf, feeding primarily on jellyfish. 

Species profiles of sea turtles, including preferred nesting locations, were presented in the Multisale EIS 

(MMS 2007b), which is incorporated by reference. The most important sea turtle nesting areas on Gulf of 

Mexico beaches are in Florida (green, loggerhead, and leatherback) and Texas (loggerhead and Kemp‘s 

ridley) (FFWCC 2010, NMFS and others 2010, Sea Turtle Restoration Project 2011; Share the Beach 

2010; BOEM 2011a). 

4.6.2 Impacts of Routine Activities on Sea Turtles

Routine IPFs that could affect sea turtles include noise and lights of the drillship and physical disturbance 

of support vessels and helicopters. IPFs resulting from accidents include a small fuel or chemical spill, a 

large oil spill, and vessel strikes (Sections 4.6.3 through 4.6.5). 

Neither permitted discharges nor marine debris is considered an IPF of the proposed action. Permitted 

discharges from the drillship and support vessels would not pose any significant impact to sea turtles 

because discharges would disperse quickly, remain localized, occur intermittently, and not contain toxic 
constituents (see Section 4.2.1.). Shell‘s standard protocols for managing marine debris would minimize

the potential for impacts to sea turtles, in compliance with NTL 2007-G03.

The Multisale EIS (MMS 2007b) and site-specific SEA S-7445 (BOEM 2011b) evaluated potential impacts 

to sea turtles. Neither noise and lights nor the physical presence of the drillship and support vessels 

were identified as IPFs for sea turtles in those documents, which are incorporated by reference into this 

EIA. NMFS concluded in its Biological Opinion that effects to sea turtles from vessel noise are 

discountable because vessel noise does not propagate far from the vessel, and sea turtles are not 

particularly attuned to auditory cues (NMFS 2007). Helicopter noise is not considered to cause a 

significant impact to sea turtles. Pilots maintain altitudes above 700 feet (213 m) during transit to and 

from the working area and do not hover over or follow sea turtles. 

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that 

would be used to drill the proposed wells works regularly in the deepwater Gulf of Mexico, moving from 

site to site as needed. The proposed action would represent a minor increase in noise, lights, and 

physical disturbance in a limited spatial area. Based on the limited spatial area and temporary nature of 

the disturbance in the context of the overall Gulf of Mexico environment, the routine IPFs associated with 

the proposed action is not likely to adversely affect sea turtles. 

Some sea turtles, especially loggerheads, have been observed preferentially congregating near offshore 

structures (Lohoefener and others 1990). The turtles‘ attraction to structures such as oil platforms 

supports the conclusion that these animals are not adversely affected by the noise, lights, and activities 

associated with oil and gas exploration. Although artificial lighting is known to disrupt the orientation 

behavior of nesting females and hatchlings emerging from nests, lighting is not a key orientation cue in 

offshore waters (Witherington 1997, Tuxbury and Salmon 2005, Salmon and Wyneken 1990). Likewise, 

NMFS (2007) concluded that the effect of lighting from the drillship on sea turtles is insignificant. 

4.6.3 Impacts of a Small Fuel or Chemical Spill in Sea Turtles

The potential for a small fuel or chemical spill to adversely affect sea turtles was evaluated in regional 

Multisale EISs (MMS 2007b, 2008; BOEM 2011a) and in NMFS‘s 2007 Biological Opinion for the Five-Year 

Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. The 

scientific literature on the impacts of fuel and oil spills on sea turtles is reviewed within the EISs and the 

Biological Opinion and is incorporated by reference into this EIA. The proposed action does not include 

any unique or unusual activities that were not evaluated in the regional EISs and the Biological Opinion. 

There are no unique site-specific issues with respect to spill impacts on sea turtles for this Initial EP.

Shell‘s rigorous training program and standard operating procedures minimize the incidence of fuel and 

chemical spills. If a small fuel or chemical spill were to occur, it would be quickly contained and cleaned 

up in accordance with Shell‘s OSRP, as described in Initial EP Sections 2j and 9b. 

A small fuel or chemical spill would disperse quickly, remain localized, occur intermittently, and not 

contain toxic constituents at levels that could cause irreversible adverse effects in sea turtles. Most sea 

turtles remain in coastal waters and would not occur in the vicinity of the drillship. The project area is 

79 miles (127 km) from the nearest shoreline in Louisiana and a large distance from important sea turtle 

nesting beaches in Texas and Florida. A small fuel or chemical spill would not be expected to make 

landfall or reach coastal waters before it broke up.

For these reasons, a small fuel or chemical spill would not adversely affect sea turtles. As described in 

Section 2.2.1, the most common fuel spill is diesel, which remains near the water‘s surface and dissipates

rapidly (NOAA 2006). A sea turtle exposed to diesel in the water could experience skin irritation and 

sloughing; inhalation of toxic fumes leading to temporary changes in blood chemistry; ingestion of oil 

directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft 

(NOAA 2003, NMFS 2010b). The small likelihood of occurrence, the limited spatial extent of the project 
area, the temporary nature of a small fuel or chemical spill, and the low density of sea turtles in the 

project area make it highly improbable that sea turtles would actually be exposed to a small spill. For 

these reasons, a small spill is not likely to adversely affect sea turtles.

4.6.4 Impacts of a Large Oil Spill on Sea Turtles

A blowout leading to a large oil spill could adversely affect sea turtles directly and indirectly. Individual 

sea turtles that are in the immediate area when a blowout occurs could be harassed, injured, or killed. A 

high concentration of response vessels could place sea turtles at a greater risk of fatal injuries from 

vessel collisions (discussed in Section 4.6.5). 

A large oil spill could have immediate direct and subsequent indirect adverse effects on sea turtles. 

Immediate direct adverse effects could include exposure to oil through dermal, ingestion, and inhalation 

pathways. Indirect adverse effects of the spill could include ingestion of contaminated prey and 

subsequent intestinal blockages (NMFS 2003). 

Dermal exposure of sea turtles to spilled oil could cause sloughing of skin, especially around the neck, 

leading to infection. Sea turtles are also vulnerable to inhalation of toxic fumes during an oil spill. They 

inhale deeply before diving and resurface frequently. Neither juvenile nor adult sea turtles appear to 

actively avoid oil spill areas, making them vulnerable to repeated bouts of inhalation if the spill covers a 

large area. Inhalation of petroleum vapors can cause temporary changes in the turtle‘s blood chemistry 

(NOAA 2003).

Sea turtles exposed to a large spill would ingest oil directly and with contaminated prey. Sea turtles 

appear to continue congregating and feeding in convergence zones even when oil is present. The oil 

ingested by a turtle takes several days to pass through the gut. Prolonged contact of the ingested oil 

with internal membranes increases the absorption of toxic constituents. Turtles that have ingested oil are 

more likely to suffer secondary physical impaction of the intestines, leading to physical distress and even 

starvation (NOAA 2003). Turtles may be affected for some time after a spill because they readily eat 

tarballs, which cause adverse effects including gut blockage, toxicity, bloating, and difficulties maintaining 

buoyancy. All of these effects increase the turtles‘ susceptibility to predation and vessel strikes (NOAA 

2003).

Toxic effects of oil exposure through all pathways include impairment of the immune and reproductive 

systems, physiological stress, declining physical condition, and death. They experience repeated, 

prolonged exposure to oil in the water and in their food because sea turtles do not exhibit behavioral 

avoidance of oiled waters. Indirect effects of a large spill on sea turtles include declines in the availability 

or quality of prey, long-term immune deficiencies, and disturbance of reproductive patterns (NOAA 2003; 

NMFS 2007).

In addition to impacts of the oil spill itself, the human response effort could also stress sea turtles (NOAA 

2003, 2010). Increased vessel, helicopter, and fixed-wing aircraft traffic would introduce additional noise 

and risk of vessel strikes. Response vessels would operate in accordance with NTL 2007-G04 to reduce 

the potential for striking or disturbing sea turtles. Marine debris in the form of containment materials 

could result in ingestion and entanglement problems. Sea turtles tend to eat anything of the appropriate 

size, including plastic. Use of dispersants could cause additional direct toxicity to the sea turtles or 

interrupt the food web that supports them (NOAA 2003, 2010; NMFS 2007).

The likelihood of any or all of these impacts actually occurring depends on the period of exposure, the 

condition of the individual turtle before exposure, and the characteristics of the spilled oil. The most 

likely direct impact would be through the inhalation pathway during the early phase of the spill. Inhaled 

fumes absorbed into the sea turtles‘ bloodstream can cause a cascade of physiological effects (NOAA 

2003). 
Individual sea turtles could be adversely affected by a large spill under the proposed action. However, a 

large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention 

measures (see Initial EP Section 2j). In the event that a blowout did occur, Shell‘s spill response 

measures would minimize the impacts by immediately containing and recovering the oil. Initial 

EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant spill 

impacts on sea turtles are expected. 

Oil from a large spill could reach the shorelines in Louisiana, Mississippi, Alabama, and Florida, where 

some sea turtle nesting occurs (Share the Beach 2010). The OSRA model predicts a 21 percent 

probability that this area could receive oil within 30 days of a large release (Table 4). The effect of 

spilled oil on sea turtle nests depends on the timing of the spill with respect to nesting. If the beach is 

already oiled, the female may choose not to nest there, or to forego nesting entirely that year. If the 

water is oily at the time the hatchlings emerge, the hatchlings would be directly exposed via all of the 

pathways described above (NOAA 2003; NMFS 2007).

Oiled and dead sea turtles were collected for several months after the DWH event. Researchers are still 

performing necropsies, and it may be some time before the total number of mortalities is known. At this 

time, approximately 600 turtle mortalities have been reported associated with the oil spill. More than 75 

percent of the mortalities were Kemp‘s ridley turtles. Smaller numbers of loggerhead and green turtles 

were reported killed. An additional 400 or so oiled turtles were collected, cleaned, and released back to 

the wild (NOAA 2011). Almost 300 turtle nests were translocated (271 loggerhead, four Kemp‘s ridley, 

and three green turtles) and more than 14,000 hatchlings were released into clean waters to protect 

them from the oil spill (NMFS 2010b).

Individual sea turtles could be adversely affected by a large oil spill under the proposed action. However, 

a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention 

measures (see Initial EP Section 2j). In the event that a blowout did occur, Shell‘s spill response 

measures would minimize the impacts by immediately containing and recovering the oil. Initial 

EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, the proposed action is 

not likely to adversely affect sea turtles.

4.6.5 Impact of Vessel Strikes on Sea Turtles

Collisions with vessels are a common cause of injury to sea turtles. Vessel-related injuries are more likely 

to occur in areas with high boating traffic (NMFS and FWS 2009). Although sea turtles likely hear and 

see approaching vessels, they may not be able to avoid all collisions. High-speed collisions with large 

vessels can be fatal to sea turtles. The risk probability of a physical strike is related to the size and speed 

on the vessel, with larger, faster vessels causing substantially more injury than smaller vessels. 

The reaction of a sea turtle to a collision would depend on the severity of the collision. Minor strikes 

would cause temporary reversible effects, such as diverting the turtle from its previous activity or causing 

short-term pain. Major strikes are those that can cause permanent injury or death from bleeding, 

infection, or inability to feed. Apart from the severity of the physical strike, the likelihood and rate of a 

turtle‘s recovery from a strike may be influenced by its age, reproductive state, and general condition. 

Much of what is written about recovery from vessel strikes is inferred from observing individuals some 

time after a strike. Numerous sea turtles bear scars that appear to have been caused by propeller cuts or 

collisions with vessel hulls (Lutcavage and others 1997; Hazel and others 2007). Conversely, fresh 

wounds on some stranded animals may strongly suggest a vessel strike as the cause of death. The 

actual incidence of recovery versus death cannot be inferred from available data. 

Shell‘s compliance with BOEM‘s protective measures, outlined in NTL 2007-G04, reduces the potential for 

collisions between vessels and sea turtles. Vessel operators are trained to identify and avoid sea turtles 

to the extent practicable, maintaining a distance of at least 150 feet (45 m). Given the protective 

measures and the relatively low chance of an encounter between sea turtles and support vessels over 
deep waters, vessel strikes near the project site are unlikely. The likelihood of strikes increases in coastal 

waters, but vessels operate in defined boat lanes near shore. Boating lanes are designated in areas 

without the habitat features that may attract sea turtles, reducing the likelihood of vessel strikes. 

The Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western 

Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007-G04 would reduce the 

likelihood of collisions between vessels and sea turtles to insignificant levels (NMFS 2007). 

The proposed action is not expected to result in any significant effect on breeding, feeding, or sheltering 

to individual sea turtles or have any consequences to populations of turtles. Shell‘s compliance with all 

mitigation and protective measures would reduce the potential for adverse effects on sea turtles to nonsignificant levels.

4.7 Coastal and Marine Birds and Critical Habitat

Dozens of marine and coastal avian species occur in the northern Gulf of Mexico. Although some species 

are more ―marine‖ and others more ―coastal,‖ these general distributional categories overlap. Coastal 

birds sometimes occur over offshore waters, especially when migrating. Conversely, many marine 

(pelagic) species nest on the coast. The time of year in which a spill occurred would have a great 

influence on the types and numbers of birds that were affected, as many species in the project area are 

migrants that occur in the area during only part of the year, and even year-round residents may change 

habitats throughout the year. Avian species and their critical habitat protected under the ESA are 

evaluated in Section 4.7.1 (Table 7); impacts to other coastal and marine birds are discussed in Section 

4.7.2.

4.7.1 Threatened and Endangered Birds

Potential impacts of the proposed action on the threatened piping plover and the endangered whooping 

crane were analyzed in the Multisale EIS (MMS 2007b) and the site-specific SEA S-7445 (BOEM 2011b). 

Additional information made available since the publication of those documents is included below. 

Table 7. Federally Listed Birds in the Northern Gulf of Mexico

Birds Scientific Name Status Designated Critical Habitat

Piping Plover Charadrius melodus Threatened All Gulf of Mexico Coastal States

Whooping Crane Grus americana

Endangered Coastal Texas (Aransas National 

Wildlife Refuge)

4.7.1.1 Piping Plover 

The piping plover is federally-listed as threatened in all Gulf of Mexico coastal states. The piping plover is 

a small, stocky, light-colored shorebird with distinctive orange legs, a black neck band, and a black brow 

during the breeding season. The piping plover inhabits and feeds in coastal and island beaches, 

mudflats, and sandflats. Individuals that overwinter on the Gulf of Mexico coast may belong to any of 

three populations that breed in the Great Lakes, the Northern Great Plains, or the Atlantic coast (FWS 

2009a). The Great Plains population is listed as endangered and the other two as threatened. Major 

threats to the piping plover are habitat loss and degradation resulting from coastal development, 

disturbance by humans and pets, and predation (FWS 2009a). Critical overwintering habitat has been 

designated on shorelines of all Gulf Coast states (Figure 3). This bird feeds on retreating tides by probing 

for invertebrates at or just below the ground surface. It roosts, rests, and preens on beaches above 

where it forages (FWS 2010a). Additional species description is available in the Multisale EIS (MMS 

2007b).
In the extremely unlikely event of a large oil spill, oil from the project area could reach piping plover 

critical habitat in Louisiana, Mississippi, Alabama, and the Florida Panhandle within 30 days. The lease 

area is 79 miles (127 km) from the nearest piping plover habitat in Plaquemines Parish, Louisiana 

(Table 4).

If oil were to reach the beaches where the piping plover overwinters, birds could become externally oiled 

while roosting or foraging. They could also ingest oil as they forage along tidal channels and shorelines 

at the water‘s edge. They would be expected to incidentally ingest oil adsorbed to the sediment and to 

take in oil as they preen. Some piping plovers could suffer illness or death if exposed to substantial 

amounts of oil. More individuals would be affected if a large spill occurred during winter when the plover 

is most abundant in the area. Degradation of critical habitat could occur during any season, but the 

degree of harm would depend on the opportunity for the habitat to recover before the birds returned in 

the fall. In addition to the direct effects of oil on the shoreline, vehicular traffic and other human 

activities associated with the spill response could adversely affect the piping plover or degrade its critical 

habitat. Shell‘s commitment and available resources to protect and rehabilitate wildlife in the event of a 

spill are described in its OSRP.

Individual piping plovers could be adversely affected by a large oil spill under the proposed action. 

However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout 

prevention measures (see Initial EP Section 2j). In the event that a large oil spill did occur, Shell‘s 

spill response measures would minimize the impacts by immediately containing and recovering the oil. 

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, the action is not 

likely to adversely affect the piping plover or to result in any degradation of its critical habitat.

4.7.1.2 Whooping Crane

The federally listed endangered whooping crane is a large omnivorous wading bird. Most of the freeranging whooping cranes in the world winter on the Aransas National Wildlife Refuge (NWR) in Texas and 

breed in Canada. As of December, 2008, a total of 270 individuals were recorded there (Whooping Crane 

Eastern Partnership [WCEP] 2010). Other populations have been established in Florida and Wisconsin in 

an attempt to secure the species. Historically, the whooping crane occurred widely in many types of 

wetland habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows 

and rivers, and agricultural fields (FWS 2007, WCEP 2010). Critical habitat designated in the Aransas 

NWR and adjacent islands provides important wintering grounds for the whooping crane (Figure 3). 

Additional information on the whooping crane is in the Multisale EISs (MMS 2007b; BOEM 2011a). 

The OSRA model shows that oil from the project area would not reach whooping crane critical habitat 

within 30 days. The project area is approximately 520 miles (837 km) from the Matagorda Unit of the 

Aransas NWR, Texas, where the whooping crane occurs. The oil is not expected to reach the shorelines 

of Matagorda County, Texas, which is an ―area of interest‖ for the whooping crane population (FWS 

2009b). The proposed action would have no effect on the whooping crane because oil is not expected to 

reach the shoreline where the crane overwinters. 
Figure 3. Critical Habitat and Essential Fish Habitat in the Northern Gulf of Mexico

4.7.2 Other Coastal and Marine Birds

Birds not protected under the ESA may be protected under the Migratory Bird Treaty Act and various 

state wildlife statutes. The northern Gulf of Mexico provides habitat for both resident and migratory birds. 

4.7.2.1 Baseline Conditions

Common marine birds in the northern Gulf of Mexico include summer non-breeding migrants 

(shearwaters, storm petrels, and boobies); summer breeding residents (sooty tern, least tern, sandwich 

tern, and magnificent frigatebird); winter non-breeding residents (gannets, gulls, and jaegers); and 

permanent breeding residents (laughing gull, royal tern, and bridled tern) (Hess and Ribic 2000). Marine 

birds range widely across the Gulf and are not associated with any particular offshore location. Terns, 

storm-petrels, shearwaters, and jaegers are the most likely to occur near the wellsite based on the water 

depth and distance from shore.

During spring and fall migration seasons, some coastal birds may occur near the well site as they make 

way across the Gulf of Mexico. Some individuals may stop to rest on offshore structures, although they 

are less likely to rest on a drillship than on a fixed platform (Russell 2005). 
Numerous coastal birds occur along the northern Gulf of Mexico coast, including diving birds, shorebirds, 

marsh birds, wading birds, and waterfowl. Beaches, flats, dunes, bars, barrier islands, and similar 

habitats support nesting sites for the sandwich tern, Wilson‘s plover, black skimmer, Forster‘s tern, gullbilled tern, laughing gull, least tern, and royal tern (FWS 2010b). These species are considered especially 

vulnerable to a large oil spill that occurs during the breeding season, as described in the Multisale EISs 

(MMS 2007b, 2008) and the site-specific SEA S-7445 (BOEM 2011b).

Although the brown pelican (Pelecanus occidentalis) was delisted from federal endangered status in 

2009, it is still given special protection by the States of Mississippi and Florida (Mississippi Department of 

Wildlife, Fisheries and Parks 2011; FFWCC 2010). The brown pelican occurs primarily in coastal habitats 

and is rare in offshore waters (Fritts and Reynolds 1981, Peake 1996, Hess and Ribic 2000). It is a yearround resident of the Gulf Coast that nests on barrier islands. 

4.7.2.2 Impacts of a Large Oil Spill on Other Coastal and Marine Birds

The only potential IPF for coastal and marine birds is a large oil spill, which would expose a variety of 

species to oil (and possibly dispersants) via dermal, inhalation, and ingestion pathways. The effects of 

exposure to oil and dispersants vary among species, and are also mediated by the individual‘s age, 

physiological condition, reproductive status, and other variables. 

Impacts of a large oil spill would be experienced first by birds in the open waters near the wellsite. Birds 

may be physically disturbed by the blowout and surge of human activity during the response phase. 

Individual birds that did not leave the area in reaction to the physical disturbance would then become 

vulnerable to the direct effects of the oil, which could result from dermal, inhalation, and ingestion 

exposure. Both marine and coastal bird species were reported to be oiled during and after the DWH 

event (FWS 2010c). Coastal birds could be affected by a large spill within 30 days, based on the 

projected trajectory of the spill (Table 4). Approximately 5,000 dead birds and 2,000 live but oiled birds 

were collected during and after the spill (FWS 2010d). The most commonly collected oiled birds were

laughing gull, Northern gannet, brown pelican, royal tern, black skimmer, and least tern. Other gulls and 

terns were also affected. The greatest numbers of avian mortalities were laughing gulls, brown pelicans, 

and northern gannets (FWS 2010d).

Like birds in the deeper waters, birds in nearshore habitats can be exposed to oil dermally or through 

ingestion. Inhalation is not expected to be a significant pathway for coastal birds because the more 

volatile constituents in the oil would have had time to dissipate before the oil spill reached the coast. 

Direct exposure to oil may cause mortality. When their feathers absorb oil, birds may lose their ability to 

fly, thermoregulate, and maintain buoyancy control when diving (FWS 2010e). Many oiled birds drown. 

If the spill occurs in winter, birds may die of hypothermia. Oil can cause an egg not to hatch by 

interfering with the gas exchange necessary to sustain the developing embryo. Direct toxicological effects 

to developing embryos vary with respect to the weathering of the oil and the age of the exposed embryo 

(Finch and others 2011). Freshly spilled oil is the most toxic to bird eggs.

Birds may ingest oil directly while foraging or preening or indirectly through their food. Once ingested, oil 

may cause immediate toxic effects or physical obstruction of the gut that leads to death by starvation. 

Ingested oil may impair lung, liver, and kidney functions, leading to death from disease, starvation, or 

predation. More than 300 brown pelican mortalities were reported after the DWH event. Potential 

causes of death included direct contact with oil, disturbance by cleanup activities, and ingestion of 

contaminated media (FWS 2010e; Finch and others 2011).

The actual extent of oiling in coastal habitats depends on the duration of the spill, meteorological 

conditions at the time, and the effectiveness of the response. Rigorous containment measures developed 

since the DWH event make it highly unlikely that such a widespread spill would occur again. 
Individual marine and coastal birds could be adversely affected by a large oil spill under the proposed 

action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control and 

blowout prevention measures (see Initial EP Section 2j). In the event that a blowout did occur, Shell‘s 

spill response measures would minimize the impacts by immediately containing and recovering the oil. 

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant 

population-level impacts to coastal or marine birds would result from a large oil spill.

4.8 Marine Mammals

This section discusses all marine mammals that occur in the northern Gulf of Mexico. All marine 

mammals are protected under the MMPA; some are also listed as endangered or threatened under the 

ESA.

Seven of the 29 species of marine mammals in the Gulf of Mexico are federally-listed as endangered 

(Table 8). The FWS has jurisdiction over the manatee; other endangered marine mammals in the Gulf of 

Mexico are the responsibility of NMFS. The FWS has designated critical habitat only for the manatee in 

peninsular Florida. No critical habitat for whales has been designated in the Gulf of Mexico. 

Table 8. Federally Endangered Marine Mammals in the Northern Gulf of Mexico

Marine Mammals Scientific Name Potential Presence

Lease Area Coastal

Odontocete (Toothed) Whales

Sperm whale Physeter macrocephalus X --

Mysticete (Baleen) Whales

Blue whale Balaenoptera musculus X

a

--

Fin whale Balaenoptera physalus X

a

--

Humpback whale Megaptera novaeangliae X

a

--

North Atlantic right whale Eubalaena glacialis X

a

--

Sei whale Balaenoptera borealis X

a

--

Sirenians

Florida manatee Trichechus manatus latirostris -- X

a

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

of Mexico and are unlikely to occur in the lease area (Würsig and others 2000).

4.8.1 Sperm Whale

The sperm whale is discussed in greatest detail in this EIA because it is the most common large whale in 

the northern Gulf of Mexico, it is federally listed as endangered, and NMFS has recently prepared a 

Biological Opinion on the sperm whale relevant to the proposed action (NMFS 2007) and a 5-year review 

and final recovery plan for the species (NMFS 2009b, 2010c). However, the IPFs and adverse effects 

described for the sperm whale also are applicable to most other marine mammals in the project area. 

Other marine mammals are discussed in subsequent sections only to the extent that effects differ from 

those described for the sperm whale .

4.8.1.1 Baseline Conditions

The sperm whale is the most common large whale in the Gulf of Mexico and the only endangered marine 

mammal likely to occur near the project area (NMFS 2009b). The year-round presence of sperm whales 

in the northern Gulf of Mexico indicates that this population may be ―resident,‖ meaning that individuals 

remain in the Gulf throughout their lives (NMFS 2009b). The sperm whale is most abundant in waters at 

least 3,280 feet (1,000 m) deep near steep gradients (NMFS 2009b and references within).
The Multisale EIS provides a description of the biology, life history, and distribution of the sperm whale, 

which is incorporated by reference (MMS 2007b; BOEM 2011a). Sperm whales move about the Gulf of 

Mexico in response to physical features such as the Gulf of Mexico Loop Current, upwellings, and other 

large-scale oceanographic conditions (Jochens and others 2008). Female sperm whales tend to remain 

along the upper continental slope between the 656- and 3,280-foot (200- and 1,000-m) depth contours, 

whereas males occur on the upper slope as well as in waters more than 9,843 feet (3,000 m) deep. 

Sperm whales often occur in groups of about 10 individuals that may or may not be genetically related to 

each other. Groups of females with young may include relatives; groups of young bachelor males 

generally include individuals who are unrelated to each other (Jochens and others 2008). The area of 

greatest sperm whale density is north of the proposed project area in waters about 3,280 feet (1,000 m) 

deep. Adult male sperm whales may transit through the deeper waters of the project area, but are not 

expected to be abundant there (Jochens and others 2008).

Routine IPFs potentially affecting the sperm whale include noise and lights and physical disturbance of 

support vessels and helicopters. IPFs resulting from accidents include a small fuel or chemical spill, a 

large oil spill, and vessel strikes. 

Neither permitted discharges nor marine debris is considered an IPF for the sperm whale. Permitted 

discharges from the drillship and support vessels would not pose any significant impact to the sperm 

whale because they would disperse quickly, remain localized, occur intermittently, and not contain toxic 

constituents (see Section 4.2.2). Shell‘s standard protocols for managing marine debris would minimize 

the potential for impacts to sperm whales, in compliance with NTL 2007-G03.

4.8.1.2 Impacts of Routine Activities on the Sperm Whale

The potential impacts of routine activities associated with oil and gas exploration on the sperm whale 

were evaluated by NMFS during its review of the EIS for the Five-Year Oil and Gas Leasing Program in 

the Central and Western Planning Areas of the Gulf of Mexico. NMFS prepared a Biological Opinion 

concluding that drilling noise and other associated activities were not likely to adversely affect the sperm 

whale (NMFS 2007). Drilling typically produces low sound source levels with amplitudes too low to 

induce adverse effects in sperm whales (NMFS 2007). This position was reiterated in the 5-year review 

of the status of the sperm whale, where NMFS reported that oil and gas exploration are ―believed to 

represent a relatively low level of threat at the current abundance of sperm whales‖ (NMFS 2009b).

Helicopter traffic associated with offshore oil and gas exploration was analyzed for potential effects on 

the sperm whale. Sperm whales react behaviorally to helicopter overflights, but their reactions are not 

considered adverse effects (MMS 2007b, Smultea and others 2008). Helicopters supporting the proposed 

action would maintain altitudes above 700 feet (213 m) during transit to and from the working area. 

Helicopter pilots do not typically approach or circle whales in the Gulf of Mexico during routine support 

flights. A whale may pause and dive during the brief period the helicopter is flying over, but this shortterm behavioral effect is considered minor and temporary, with no long-term biological significance.

The resident sperm whales in the Gulf of Mexico are exposed to noise, lights, and physical activity 

associated with oil and gas exploration, commercial fishing, and shipping. A study of the effects of small 

boats (whale watching tour boats) on the behavior of sperm whales in the Southern Ocean indicated that 

whales become increasingly tolerant of the vessels when exposure is frequent (NMFS 2009b). The supply 

vessels that support the rigs and platforms may elicit similar habituation in sperm whales in areas of the 

northern Gulf of Mexico where oil and gas activity is concentrated. (Habituation is the process whereby 

an animal ―ignores‖ a stimulus because it has learned that no response is warranted.) 

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that 

would be used to drill the proposed wells works regularly in the deepwater Gulf of Mexico, moving from 

site to site as needed. The proposed action would represent a minor increase in noise, lights, and 
physical disturbance to a limited spatial area. Based on the limited spatial area and temporary nature of 

the disturbance in the context of the overall Gulf of Mexico environment, the proposed action would not 

adversely affect the sperm whale.

Although noise, lights, and physical disturbance of the drillship and support vessels were considered 

potential factors affecting sperm whales, NMFS‘s Biological Opinion and 5-year review support the 

conclusion that these activities are not IPFs for the sperm whale (NMFS 2007, 2009a). Exclusion of these 

activities as IPFs for the sperm whale is consistent with recent Multisale EISs (MMS 2007b, 2008; BOEM

2011a).

4.8.1.3 Impacts of a Small Fuel or Chemical Spill on the Sperm Whale

The potential for a small fuel or chemical spill to adversely affect the sperm whale was evaluated in the 

regional Multisale EISs (MMS 2007b, 2008; BOEM 2011a) and in NMFS‘s 2007 Biological Opinion for the 

Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. 

The scientific literature on the impacts of fuel and oil spills on marine mammals is reviewed in the EISs 

and the Biological Opinion and is incorporated by reference into this EIA. The proposed action does not 

include any unique or unusual activities that were not evaluated in the regional Multisale EISs and the 

Biological Opinion. 

Shell‘s rigorous training program and standard operating procedures minimize the incidence of fuel and 

chemical spills. If a small fuel or chemical spill were to occur, it would be quickly contained and cleaned 

up in accordance with Shell‘s OSRP, as described in Initial EP Sections 2j and 9b. 

A small fuel or chemical spill would disperse quickly, remain localized, occur intermittently, and not 

contain toxic constituents. For these reasons, a small fuel or chemical spill would not adversely affect the 

sperm whale. As described in Section 2.2.1, the most common fuel spill is diesel, which remains the 

water‘s surface and dissipates rapidly (NOAA 2006). 

A sperm whale exposed to diesel in the water could experience skin irritation, inflammation, or necrosis; 

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). The small likelihood of occurrence, the limited spatial extent 

of the project area, the temporary nature of a small fuel or chemical spill, and the ability of sperm whales 

to detect and avoid spill areas make it highly improbable that a sperm whale would actually be exposed 

to a small spill. For these reasons, no significant adverse effects on the sperm whale would result from a 

small spill during the proposed action.

4.8.1.4 Impacts of a Large Oil Spill on the Sperm Whale

A blowout causing a large oil spill could have immediate direct and subsequent indirect adverse effects on 

the sperm whale. Immediate direct adverse effects would include exposure to the oil through dermal, 

ingestion, and inhalation pathways. Indirect adverse effects of the spill could include ingestion of 

contaminated prey, interruption of foraging opportunities, and displacement from feeding areas 

(Geraci and St. Aubin 1987). 

Dermal exposure to spilled oil could cause skin irritation, inflammation, necrosis, and chemical burns. 

Whale skin is protected from dermal absorption by tight intercellular bridges, a thick epidermis, and the 

absence of sweat glands and hair follicles that would allow entry to subdermal layers. The epidermis of 

whales effectively excludes most constituents of petroleum (Geraci and St. Aubin 1985). Whales do not 

ingest oil while grooming or preening as do many other mammals and birds. However, they may ingest 

oil and dispersants incidentally while foraging and in contaminated prey. Marine mammals are not 

particularly sensitive to ingested diesel or other petroleum compounds (Neff 1990).
Whales may be exposed to toxic constituents in oil through inhalation, especially during the initial stages 

of a large spill. Inhalation of petroleum fumes could cause respiratory distress. Cetacean respiratory 

membranes are sensitive to hydrocarbon fumes, and toxic components of the oil can be absorbed by the 

bloodstream (Geraci and St. Aubin 1987). 

Toxic effects of oil exposure through all pathways include impairment of the immune and reproductive 

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

displacement of animals from prime habitat, disruption of social structure, reduced availability or quality 

of prey, interrupted reproductive behavior, and disturbance to typical patterns of movement or migration 

(MMC 2010).

In addition to impacts of the oil spill itself, the human response effort could also affect the sperm whale. 

Increased vessel, helicopter, and fixed-wing aircraft traffic would introduce additional noise and risk of 

vessel strikes. Response vessels would operate in accordance with NTL 2007-G04 to reduce the potential 

for striking or disturbing marine mammals. Marine debris in the form of containment materials could 

result in ingestion and entanglement problems. Use of dispersants could cause additional direct toxicity 

to the sperm whales or interrupt the food web that supports the whale (MMC 2010). 

The likelihood of any or all of these impacts actually occurring depends on the period of exposure, the 

condition of the individual whale before exposure, and the characteristics of the spilled oil. The most 

likely direct impact would be through the inhalation pathway, as the whale‘s respiratory membranes are 

sensitive to hydrocarbon fumes, and toxic components of the oil can be absorbed by the bloodstream 

(Geraci and St. Aubin 1987). Interruption of the whale‘s foraging behavior, either by physical 

displacement or contamination, could occur, but is of less concern because the whales are highly mobile 

and extensive alternative foraging areas would be available (BOEM 2011a).

Individual sperm whales could be adversely affected by a large oil spill under the proposed action. 

However, a large spill is extremely unlikely to occur because Shell has established rigorous well control 

and blowout prevention measures (see Initial EP Section 2j). In the event that a blowout did occur, 

Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the 

oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, a large spill 

is not likely to adversely the sperm whale. 

4.8.1.5 Impacts of Vessel Strikes on the Sperm Whale

Vessel strikes are reported to threaten the recovery of the sperm whale. The most recent 5-year status 

review reported that sperm whales continue to be injured or killed by collisions with vessels. However, 

the incident rate and level of threat are low (NMFS 2009b). 

Although a sperm whale is vulnerable to vessel strikes when it is ―rafting‖ at the surface for up to 10-

minute intervals between long dives (NMFS 2009b), it is not particularly susceptible to vessel strikes 

compared with other large whales. A study of 292 strikes of all large whales worldwide included only 17 

collisions with sperm whales (13 mortalities) (Laist and others 2001, Jensen and Silber 2004). Most 

collisions are with large vessels such as Navy ships, container and cargo ships, whale-watching vessels, 

cruise ships, ferries, USCG vessels, and tankers (Jensen and Silber 2004). Large (more than 80 m) fastmoving (more than 14 knots) vessels pose the greatest risk of injury or death to the whales (Laist and 

others 2001). USCG and NMFS regulations on marine mammal awareness and speed limits have reduced 

the incidence of vessel strikes in U.S. waters (NMFS 2009b). 

The reaction of a marine mammal to being struck by a vessel would depend on the severity of the 

collision. Minor strikes would cause temporary reversible effects, such as diverting the individual from its 

previous activity, causing transient pain, or separation from a group. Major strikes are those that can 

cause permanent injury or death. Apart from the severity of the physical strike, the likelihood and rate of 
an individual‘s recovery from a strike may be influenced by its age, sex, reproductive state, and general 

condition. Much of what is written about recovery from vessel strikes is inferred from observing 

individuals some time after the strike occurred. Numerous marine mammals bear scars that appear to 

have been caused by propeller cuts or collisions with vessel hulls. Conversely, fresh wounds such as 

propeller wounds on some stranded animals suggest a vessel strike as the cause of morbidity or 

mortality. Data from necropsies from dead stranded animals sometimes show massive internal injuries 

consistent with ship strikes. The actual incidence of recovery versus death is not quantifiable, given 

available data. 

Support vessels under the proposed action are not of the class of ships that pose a substantial threat to 

large whales. Shell requires all support vessel operators to comply with protective measures instituted by 

BOEM (NTL 2007-G04), including training to identify marine mammals, maintaining watches for marine 

mammals, and avoiding collisions with marine mammals. Vessel operators are required to report 

sightings of any injured or dead marine mammal. NTL 2007-G04 provides guidance on avoiding whales, 

requiring operators to remain at least 300 feet (91 m) away from a whale when possible, and observe a 

10-knot speed limit near mother/calf pairs, pods, and other assemblages of large marine mammals when 

safety permits. 

The Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western 

Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007-G04 would reduce the 

likelihood of collisions between vessels and sperm whales to insignificant levels (NMFS 2007). The 

combination of sperm whales actively avoiding approaching vessels and operators actively avoiding 

whales results in a low incidence of collision. 

The proposed action is not expected to result in any significant effect on migration, breathing, nursing, 

breeding, feeding, or sheltering to individuals, or have any consequences at the population level. Shell‘s 

compliance with all mitigation and protective measures would reduce the potential for harassment of 

sperm whales to discountable levels (NMFS 2007). The proposed action is not likely to adversely affect 

the sperm whale. 

4.8.2 Mysticete Whales

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

whale, and sei whale) occur at least incidentally in the Gulf of Mexico but are considered rare or 

extralimital (Würsig and others 2000) (Table 5). 

These whales are so uncommon in the Gulf of Mexico that NMFS did not include them in its Biological 

Opinion on the potential for oil and gas activities to adversely affect endangered marine mammals (NMFS 

2007). Potential impacts to mysticetes were analyzed and found not to be significant in the regional 

Multisale EISs (MMS 2007b, 2008), which are incorporated by reference into this EIA. In the unlikely 

event that individual mysticete whales were present in the project area, expected impacts would be 

comparable to those described for the sperm whale in Section 4.8.1. The geographic scope and limited 

duration of the proposed action make it extremely unlikely to result in any significant adverse effects on 

endangered mysticete whales.

4.8.3 West Indian Manatee

The West Indian manatee includes two subspecies: the Florida manatee (Trichechus manatus latirostris) 

and the Antillean manatee (T. m. manatus). The entire species is federally listed as endangered, but only 

the Florida manatee occurs in the project area. The Florida manatee is depleted under the MMPA. Much 

of the general literature on manatees is not particular to one subspecies and is assumed to pertain to the 

Florida manatee. The West Indian manatee typically inhabits only coastal marine, brackish, and

freshwater areas. Manatees occur in very shallow water depths 6.6 to 13.1 feet (2 to 4 meters) close to 

shore because of their preferred diet of sea grasses, which need high light levels to grow (FWS 2009c). 
During the winter, most Florida manatees remain in warmwater refugia in peninsular Florida (FWS 

2009c). In summer, individuals disperse northward up the Atlantic coast and westward into the Gulf of 

Mexico as far as Texas (Wilson 2003, Fertl and others 2005). Manatees could occur in the coastal waters 

of Louisiana only during the summer. They would never be expected to venture into the deep waters of 

the project area. 

During the short time the manatee may occur in coastal Louisiana waters, the only IPFs potentially 

affecting it are associated with support vessel and helicopter movement near the onshore facilities and a 

large oil spill. Small fuel or chemical spills in the lease area are not considered IPFs for the manatee 

because this species does not occur in deep waters. A small spill would not be transported from the 

project area to the shoreline 79 miles (127 km) away (NOAA 2006). 

4.8.3.1 Baseline Conditions of the West Indian Manatee

The West Indian manatee is a rotund slow-moving aquatic herbivorous mammal that can reach a 

maximum length of 12.8 feet (3.9 m) (Jefferson and others 2008). It usually swims slowly (1 to 4 miles 

per hour [mph]; 1.6 to 6.4 kilometers per hour) but can sprint up to 15 mph (25 km/hr). When a 

manatee is at the surface, the only exposed parts are the tip of the muzzle and a small portion of the 

upper back, which makes it difficult to observe. The manatee makes short shallow dives, rarely 

descending deeper than 65 feet (20 m) or remaining submerged for more than 3 minutes. When resting 

at the bottom, a manatee may stay submerged for up to 24 minutes (Department of the Navy 2008). 

The manatee tends to swim alone or in groups of up to six (Jefferson and others 2008).

The distribution, feeding habits, habitat use, and population estimates of manatees were described in the 

Multisale EIS (MMS 2007b). The most recent available minimum population estimate of the Florida 

manatee is 1,822 animals (Waring and others 2009). In 2011, the maximum number of Florida manatees 

was estimated at 4,834 (Florida Fish and Wildlife Conservation Commission [FFWCC] 2011).

4.8.3.2 Impacts of Routine Activities on the Manatee

The Florida manatee would not be adversely affected by routine activities associated with the proposed 

action. Movement of support vessels and helicopters may disturb but not harass or injure individuals that 

are in coastal Louisiana waters during the summer. Helicopter flyovers could disturb manatees in the 

immediate vicinity. Helicopters contracted for the proposed action would maintain a minimum altitude of 

700 feet (213 m) during offshore transit, 1,000 feet (305 m) over unpopulated areas or across coastlines, 

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

properties. Maintenance of minimum altitudes reduces the likelihood that manatees would be disturbed 

to less than significant levels.

No large congregation of manatees occurs in the coastal area near the heliport or seaport. As a coastal 

species, the manatee is exposed to background vessel noise. In fact, the manatee‘s lack of quick 

response to vessel noise accounts for its high injury rate from vessel strikes (see Section 4.8.3.4). 

However, the lack of response also suggests that noise generated by vessel movement and helicopter 

flyovers does not constitute a significant adverse effect to the Florida manatee.

4.8.3.3 Impacts of a Large Oil Spill on the Manatee

In a quantitative assessment of relative threats of human activity to the Florida manatee, vessel strikes 

and loss of warm-water habitats accounted for virtually all of the risk (Runge and others 2007). A large 

oil spill could affect the population, but the chance that one will occur is exceeding small. The lease area 

is hundreds of miles from the population center of the Florida manatee in south Florida. Most manatees 

are on the east coast of Florida, beyond the range of a spill. Some manatees congregate on the Gulf side 
of peninsular Florida, especially in winter, but even this area is well outside the range of a reasonably 

likely spill, given the rigorous response measures incorporated into the proposed action.

A small number of individual manatees in coastal waters of the northern Gulf of Mexico could be affected 

by a large oil spill in several ways: direct exposure to oil and dispersants; loss of foraging habitat by 

oiling; and vessel strikes. Effects of direct exposure to oil and dispersants are not well known in the 

manatee, but are expected to be similar to those described for the sperm whale (Section 4.8.1.4). The 

manatee may ingest more oil than the sperm whale because oil may accumulate on the shallow 

vegetation that the manatee eats. The manatee also has sensory hairs around its mouth that could 

collect oil and interfere with feeding. If the oil and dispersants (or the physical disturbance of the 

response activity) resulted in injury to shallow vegetation, the manatee could experience loss of foraging 

habitat and subsequent nutritional deficiencies (FWS 2009c).

The manatee may suffer additional stress because of the intense human activity resulting from response 

and restoration in coastal areas (BOEM 2011b). The increase in vessel traffic responding to the spill in 

coastal waters and transiting to offshore waters puts the manatee at risk, especially because operators of 

the response vessels may not be as well-trained as regular supply vessel operators in avoidance and 

protection measures for marine mammals. 

The manatee could be indirectly affected if spilled oil (or dispersants) contaminated or killed the aquatic 

vegetation that it eats. These effects on the manatee from loss of forage would be minor and temporary. 

The FWS estimated that up to 12 individual Florida manatees could be killed, in addition to natural 

mortalities, without causing serious population-level effects (FWS 2009c). Based on the low density of 

manatees in coastal waters near the project area and the unlikely occurrence of a blowout, the proposed 

action is not likely to adversely affect the Florida manatee. 

4.8.3.4 Impacts of Vessel Strikes on the Manatee

The most significant threat to the Florida manatee is collision with vessels, including direct strikes and 

propeller cuts that can result in injury or death (FWS 2009c). Watercraft-related incidents account for 25 

to 35 percent of documented deaths (FWS 2010f).

The reaction of a manatee to being struck by a vessel would depend on the severity of the collision. 

Minor strikes would cause temporary reversible effects, such as diverting the individual from its previous 

activity, causing transient pain, or separation from a group. Major strikes are those that can cause 

permanent injury or death. Apart from the severity of the physical strike, the likelihood and rate of an 

individual‘s recovery from a strike may be influenced by its age, sex, reproductive state, and general 

condition. Much of what is written about recovery from vessel strikes is inferred from observing 

individuals some time after the strike occurred. Numerous manatees bear scars that appear to have 

been caused by propeller cuts or collisions with vessel hulls. Conversely, fresh wounds such as propeller 

wounds on some stranded animals suggest a vessel strike as the cause of morbidity or mortality. Data 

from necropsies from dead stranded animals sometimes show massive internal injuries consistent with 

ship strikes. The actual incidence of recovery versus death is not quantifiable, given available data. 

Shell requires that contracted vessel operators comply with NTL 2007-G04, which mandates training on 

detecting and avoiding marine mammals. One effective avoidance technique is to reduce vessel speed 

when marine mammals are present. Both manatees and boaters have time to avoid a collision at slower 

vessel speeds. If a collision occurs at slower speeds, the injury to the manatee is less severe (FFWCC 

2007). Under routine conditions, supply vessels are not expected to strike manatees because operators 

are trained and committed to following the mitigation and conservation measures in BOEM‘s NTL 2007-

G04 and other regulations of the MMPA. Vessel strikes under the proposed action are not likely to 

adversely affect the Florida manatee. 
4.8.4 Non-Endangered Marine Mammals

In addition to the seven endangered marine mammals discussed above, 22 other species of whales and 

dolphins potentially occur in the project area (see Initial EP Section 6h) (Table 9). These species are 

protected under the MMPA but are not listed as threatened or endangered under the ESA. Life history 

data, baseline conditions, and potential impacts of oil and gas activities were presented in the Multisale 

EIS (MMS 2007b), which is incorporated by reference into this EIA. Impacts of the proposed action are 

discussed below.

Table 9. Non-endangered Marine Mammals in the Northern Gulf of Mexico

Non-Endangered Marine Mammals Scientific Name

Mysticete (Baleen) Whales

Bryde‘s whale Balaenoptera edeni

Minke whale Balaenoptera acutorostrata

Dwarf and Pygmy Sperm Whales

Pygmy sperm whale Kogia breviceps

Dwarf sperm whale Kogia sima

Beaked Whales

Cuvier‘s beaked whale Ziphius cavirostris

Blainville‘s beaked whale Mesoplodon densirostris

Sowerby‘s beaked whale Mesoplodon bidens

Gervais‘ beaked whale Mesoplodon europaeus

Delphinids (dolphins)

Killer whale Orcinus orca

Short-finned pilot whale Globicephala macrorhynchus

False killer whale Pseudorca crassidens

Pygmy killer whale Feresa attenuata

Melon-headed whale Peponocephala electra

Rough-toothed dolphin Steno bredanensis

Risso‘s dolphin Grampus griseus

Bottlenose dolphin Tursiops truncates

Pantropical spotted dolphin Stenella attenuata

Atlantic spotted dolphin Stenella frontalis

Spinner dolphin Stenella longirostris

Clymene dolphin Stenella clymene 

Striped dolphin Stenella coeruleoalba

Fraser‘s dolphin Lagenodelphis hosei

4.8.4.1 Baseline Conditions of Non-Endangered Marine Mammals

Mysticete whales. Bryde‘s whale is the only large whale other than the sperm whale considered a 

common resident of the northern Gulf of Mexico. It is most often reported in shallow coastal waters 

along the 100-m (328-foot) isobath in the DeSoto Canyon region and to the east (Davis and Fargion 

1996, Davis and others 2000). It is possible that individual Bryde‘s whales could occur in the lease area. 

The minke whale is considered rare in the Gulf of Mexico; the only confirmed records of this species in 

the northern Gulf of Mexico are from stranded individuals (Würsig and others 2000).

Dwarf and pygmy sperm whales. The dwarf sperm whale so closely resembles the pygmy sperm 

whale that the two species are generally referred to as ―Kogia spp.‖ Both species are known from the
Gulf of Mexico, primarily along the continental shelf edge and in deeper offshore waters (Mullin and 

others 1991, Mullin 2007). Both of these species could occur in the project area.

Beaked whales. All four beaked whales known to occur in the Gulf of Mexico could be present at the 

project site, as all are broadly distributed over the lower slope below 3,281 feet (1,000 m) and deeper 

(Davis and others 2000). Based on stranding records, Gervais‘ beaked whale is the most common in the 

Gulf of Mexico, and Sowerby‘s beaked whale is the least likely to occur. None of the beaked whales is 

common near the lease area. 

Delphinids. The most common marine mammals in the deepwater Gulf of Mexico are the widely 

distributed dolphins (pantropical spotted, spinner, and clymene dolphins). However, any of the 

delphinids listed in Table 9 could occur in the lease area.

4.8.4.2 Impacts of Routine Activities on Non-Endangered Marine Mammals 

The evaluation of IPFs for the endangered sperm whale applies equally to non-endangered marine 

mammals (see Section 4.8.1). Routine IPFs potentially affecting non-endangered marine mammals 

include noise and lights and physical disturbance of support vessels and helicopters. IPFs resulting from 

accidents include a small fuel or chemical spill, a large oil spill, and vessel strikes. 

Neither permitted discharges nor marine debris is considered an IPF for marine mammals. Permitted 

discharges from the drillship and support vessels would not pose any significant impact to nonendangered marine mammals because discharges would disperse quickly, remain localized, occur 

intermittently, and not contain toxic constituents (see Section 4.2.1). Shell‘s standard protocols for 

managing marine debris would minimize the potential for impacts to non-endangered marine mammals, 

in compliance with NTL 2007-G03.

The Multisale EIS (MMS 2007b) and site-specific SEA S-7445 (BOEM 2011b) evaluated potential impacts 

to non-endangered marine mammals. Neither noise and lights, nor the physical presence of the drillship 

and support vessels, were identified as IPFs for marine mammals in those documents, which are 

incorporated by reference into this EIA.

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that 

would be used to drill the proposed wells works regularly in the deepwater Gulf of Mexico, moving from 

site to site as needed. The proposed action would represent a minor increase in noise, lights, and 

physical disturbance to a limited spatial area. Based on the limited spatial area and temporary nature of 

the disturbance in the context of the overall Gulf of Mexico environment, the routine IPFs associated with 

the proposed action would not significantly affect any non-endangered marine mammals.

4.8.4.3 Impacts of a Large Oil Spill on Non-Endangered Marine Mammals

Potential impacts of a large oil spill on non-endangered marine mammals are comparable to those 

described for the sperm whale in Section 4.8.1.4 of this EIA and are consistent with conclusions reached 

in the Multisale EIS (MMS 2007b) and site-specific SEA S-7445 (BOEM 2011b). The analysis of adverse 

effects of a large oil spill on the sperm whale included generalized data on other marine mammals and so 

is considered equally applicable to non-endangered marine mammals. The proposed action does not 

include any activities that would cause unique impacts or a disproportionate effect on non-endangered 

marine mammals.

Marine mammals could be exposed to oil and dispersants via dermal absorption, ingestion, and 

inhalation, as described in Section 4.8.1.4 for the sperm whale. Data are inadequate to evaluate the 

particular sensitivity of each species to oil or dispersants. Instead, it is assumed that toxicological effects 

data are generally applicable to other marine mammals (MMC 2010). 
Marine mammals are expected to react to the increased human activity associated with the response 

action by avoiding disturbed areas. However, the specific behavioral reactions of each species are not 

well known. The protective measures required by NTL 2007-G04 for endangered marine mammals would 

serve to reduce the potential for disturbing or striking other marine mammals as well. No significant 

adverse impacts would be expected.

The likelihood of significant impacts to any individual marine mammal depends on its period of exposure, 

its physiological condition, and the toxicity of the spilled oil. Inhalation is considered the most harmful 

pathway for most marine mammals because inhaled hydrocarbon fumes can deliver toxic constituents to 

the bloodstream (Geraci and St. Aubin 1987). Interruption of the animal‘s foraging behavior, either by 

physical displacement or contamination, could occur; however, marine mammals are highly mobile, and 

extensive alternative foraging areas would be available (NMFS 2007, 2009a).

Individual marine mammals could be adversely affected by a large spill under the proposed action. 

However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout 

prevention measures (see Initial EP Section 2j). In the event that a blowout did occur, Shell‘s spill 

response measures would minimize the impacts by immediately containing and recovering the oil. 

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant 

spill impacts on marine mammals are expected.

4.8.4.4 Impacts of Vessel Strikes on Non-Endangered Marine Mammals

Vessel strikes are a recognized threat to marine mammals. The potential for non-endangered marine 

mammals to be injured or killed by vessels associated with oil and gas activities was evaluated in the 

Multisale EIS (MMS 2007b) and the site-specific SEA S-7445 (BOEM 2011b). The analysis of the effects 

of vessel strikes on endangered marine mammals in the 2007 Biological Opinion can also be extrapolated 

to the proposed action (NMFS 2007). 

The reaction of a marine mammal to being struck by a vessel would depend on the severity of the 

collision. Minor strikes would cause temporary reversible effects, such as diverting the individual from its 

previous activity, causing transient pain, or separation from a group. Major strikes are those that can 

cause permanent injury or death. Apart from the severity of the physical strike, the likelihood and rate of 

an individual‘s recovery from a strike may be influenced by its age, sex, reproductive state, and general 

condition. Much of what is written about recovery from vessel strikes is inferred from observing 

individuals some time after the strike occurred. Numerous marine mammals bear scars that appear to 

have been caused by propeller cuts or collisions with vessel hulls. Conversely, fresh wounds such as 

propeller wounds on some stranded animals suggest a vessel strike as the cause of morbidity or 

mortality. Data from necropsies from dead stranded animals sometimes show massive internal injuries 

consistent with ship strikes. The actual incidence of recovery versus death is not quantifiable, given 

available data. 

In comparison with other regions of the United States, the Gulf of Mexico is the least common area for 

vessel strikes of large whales (Jensen and Silber 2004). Between 1972 and 1999, eight confirmed or 

possible vessel strikes that involved large whales were recorded in the Gulf of Mexico, including two 

collisions with Navy vessels. Large whales may move too slowly to avoid vessels approaching at high 

speeds. Smaller species, such as dolphins, move more quickly and are less vulnerable to vessel strikes 

(BOEM 2011a). 

Support vessels under the proposed action are not of the class of ships that pose a substantial threat to 

large whales. Shell requires all support vessel operators to comply with protective measures instituted by 

BOEM (NTL 2007-G04), including training to identify marine mammals, maintaining watches for marine 

mammals, and avoiding collisions with marine mammals. Vessel operators are required to report 

sightings of any injured or dead marine mammal. NTL 2007-G04 provides guidance on avoiding whales, 
requiring operators to remain at least 300 feet (91 m) away from a whale when possible, and observe a 

10-knot speed limit near mother/calf pairs, pods, and other assemblages of large marine mammals when 

safety permits. 

The Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western 

Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007-G04 would reduce the 

likelihood of collisions between vessels and sperm whales to insignificant levels (NMFS 2007). That

conclusion can be reasonably applied to other large whales such as Byrde‘s whale. 

The proposed action is not expected to result in any significant effect on migration, breathing, nursing, 

breeding, feeding, or sheltering to individuals, or have any consequences at the population level. Shell‘s 

compliance with all mitigation and protective measures would reduce the potential for collisions with 

marine mammals to non-significant levels.

4.9 Threatened and Endangered terrestrial Species and critical habitat

Coastal habitats in the northern Gulf of Mexico support protected species that could be affected by the 

proposed action. The diamondback terrapin (species of concern) and the federally-endangered beach 

mouse are discussed below.

4.9.1 Diamondback Terrapin (Species of Concern)

The diamondback terrapin (Malaclemys terrapin) is considered a species of concern by the FWS (Federal 

Register 59, no. 219 [November 15, 1994: 58982 59028). The diamondback terrapin is the only North 

American turtle that lives entirely in estuaries (Ernst and others 1994). Although this species was not 

considered in the programmatic EIS (MMS 2007b), impacts to the diamondback terrapin are included in 

the DWH event natural resource damage assessment, leading BOEM to add this species to the 2011 SEIS 

for the Western Planning Area (BOEM 2011a). No critical habitat has been designated for the 

diamondback terrapin, but it is known to inhabit open channels within coastal marshes (Dundee and 

Rossman 1989). The Texas diamondback terrapin (Malaclemys terrapin littoralis) ranges along the coasts 

of Texas and Louisiana, and the Mississippi diamondback terrapin (M. t. pileata) occurs from Louisiana to 

Florida. Baseline conditions and potential impact discussions in the WPA SEIS (BOEM 2011a) are 

incorporated by reference. 

The WPA SEIS concluded that the only IPF that could cause a significant long-term adverse effect on the 

diamondback terrapin was a large oil spill. No collisions of service vessels with terrapins have been 

reported in the Gulf of Mexico. Routine IPFs such as marine debris and vessel traffic were determined to 

cause less than significant impacts to this species (BOEM 2011a). 

The potential impacts of a large oil spill on diamondback terrapins were not considered in the Multisale 

EISs (MMS 2007b; MMS 2008). The OSRA modeling predicts that a large oil spill would not reach 

terrapin habitat within the first 10 days, but could contact the nearest Louisiana shoreline within 30 days. 

Terrapins in more distant coastal parishes in Louisiana and to the east have a smaller but positive 

likelihood of being contacted by oil within 30 days of a large spill (Table 4). 

If oil from a large spill were to contact diamondback terrapins in their coastal habitat, individuals would 

likely experience decreased vigor, impaired reproductive success, and loss of immunity to disease, 

potentially leading to decreased lifespan (BOEM 2011a). Adverse effects on hatchling terrapins would 

likely be more severe, potentially leading to increased mortality. Baseline data on the diamondback 

terrapin are scarce, and the impacts of the DWH event on this species have not yet been quantified. 

However, the WPA SEIS reported that no impact to the diamondback terrapin has been reported during 

the more than 50 years the OCS program has been in existence (BOEM 2011a). Because a large oil spill 

is a highly unlikely event, the probability that oil would enter the coastal channels frequented by the 

diamondback terrapin is very small. Shell‘s comprehensive OSRP is focused on quickly containing and 
collecting spilled oil, which would limit the amount of oil that ultimately reached the coast. The proposed 

action is not likely to adversely affect either subspecies of diamondback terrapin. 

4.9.2 Beach Mouse

Four subspecies of a federally endangered beach mouse occur on barrier beaches in Alabama and Florida 

(Table 10); critical habitat has been designated for all of them (Figure 3). Species descriptions and 

baseline conditions are described the Multisale EIS (MMS 2007b). The principal reasons for decline of 

beach mouse populations across the Gulf Coast are habitat destruction, habitat fragmentation, domestic 

or feral predators, and highway mortality. Natural threats include hurricanes and other large coastal 

storms, flooding, and erosion of coastal habitats (FWS 2009d).

Table 10. Federally-Endangered Beach Mouse Subspecies on the Northern Gulf of Mexico 

Coast 

Coastal Animals Scientific Name

Alabama beach mouse Peromyscus polionotus ammobates

Choctawhatchee beach mouse P. p. allophrys

Perdido Key beach mouse P. p. trissyllepsis

St. Andrew beach mouse P. p. peninsularis

The nearest beach mouse critical habitat is at least 120 miles (193 km) from the project area, outside the 

range of any routine IPFs. The only IPF that could adversely affect any of the beach mouse subspecies is 

a large spill that oiled substantial portions of their beachfront habitat. 

The potential impacts of a large spill on any of the beach mouse populations are analyzed in regional 

EISs (MMS 2007b, 2008) and the site-specific SEA S-7445 for a nearby lease (BOEM 2011b). The 

proposed action would occur in the OCS at least 120 miles (193 km) from the nearest critical habitat for 

the beach mouse. Based on the trajectory predicted by the OSRA modeling, oil would not reach beach 

mouse critical habitat within 30 days of a spill (Table 4). 

A large oil spill is an exceedingly unlikely event. However, significant adverse effects could result if a spill 

were to occur and oil were to reach critical habitat for the beach mouse. Dermal contact with oil could 

irritate the skin, eyes, and mucous membranes, leading to lesions and potential infection; mat the fur, 

making it difficult for the individual to groom itself and thermoregulate; and interfere with vision and 

hearing. Inhalation of petroleum fumes could cause breathing problems and toxicity, although the 

project site is far enough away that the oil would be weathered before it reached mouse habitat. 

Ingestion of oil and contaminated food could lead to intestinal blockages and subsequent starvation. 

Indirect impacts of exposure to oil via any of these pathways include reduction of the quantity or quality 

of food, degradation of habitat, and interruption of nesting or nursing. Direct physical impacts associated 

with the cleanup effort can also adversely affect the mice and degrade their habitat. The likelihood that 

oil would reach critical for the beach mouse is low because Shell‘s comprehensive OSRP is focused on 

quickly containing and collecting spilled oil and the project site is a great distance from the mouse‘s 

critical habitat. The proposed action is not likely to adversely affect any of the subspecies of beach 

mouse or to modify or degrade any of their designated critical habitat. 

4.10 Coastal Habitats and Protected Areas

The northern Gulf of Mexico coast is a complex mosaic of marine, brackish, and freshwater habitats, 

described in the regional Multisale and Supplemental EISs (MMS 2007b, 2008) as well as in the published 

literature. Shell‘s OSRP acknowledged the variety and vulnerability of coastal habitats and focused on 

methods for reducing impacts to these areas. In the central Gulf of Mexico, the distribution of coastal 

habitats is influenced primarily by the Mississippi River, which discharges tremendous volumes of fresh 
water and sediment in a plume far out into the Gulf. West of the Mississippi River, the coast is 

dominated by fine-grained silts and muds supporting fragile marshes of varying salinities behind barrier 

islands that are in various states of degradation. East of the mouth of the river, the coast becomes 

firmer as coarser-grained sediments form true beaches protected by relatively intact barrier islands. 

Seagrass beds are rare to the west, but more abundant some distance east of the Mississippi River‘s

heavy sediment load (Moncreiff 2007). 

As mentioned in Section 4.5.3.7, most of the coastal habitat in the northern Gulf of Mexico serves as EFH 

for a wide variety of species, including commercially and recreationally important red drum, shrimp, and 

blue crab. In addition, 39 NWRs on the Gulf coast have a marine component and may be vulnerable to 

large oil spills. The NWRs occur across the coast, with 10 in Texas, seven in Louisiana, two in Mississippi, 

and 20 in Florida (FWS 2010g). The nearest NWRs to the project area are the Breton NWR and Delta 

NWR in Plaquemines Parish, Louisiana (Wilderness.net 2011). 
Figure 4. Distribution of Habitats in the Northern Gulf of Mexico
4.10.1 Impacts of Routine IPFs on Coastal Habitats

None of the routine IPFs would affect any coastal habitats because of the distance (79 miles [127 km]) of 

the project area from shore. The support bases at Port Fourchon and Amelia would continue to operate 

as they normally do, and no expansion would occur (see Initial EP Section 14). Support vessels work 

from established docks, travel in designated transit lanes, and maintain safe speeds in no-wake zones, as 

required. Support vessels for the proposed action are comparable to vessels used for other oil and gas 

activities, offshore fishing, and other offshore enterprises. Support vessels would not cause significant 

impacts to coastal habitats. 

4.10.2 Impacts of a Large Oil Spill on Coastal Habitats

A blowout could release a substantial volume of oil in the Gulf, as described in Initial EP Section 2j. 

Regional EISs analyzed the potential impacts of large oil spills on coastal habitats, including barrier 

beaches and dunes, wetlands, and submerged seagrass beds (MMS 2007b, 2008). The proposed action 

does not introduce any unique activities that would cause additional impacts to coastal habitats. 

The OSRA modeling results show that Plaquemines Parish, Louisiana, has the greatest chance (21 

percent) of being affected by a large oil spill within 30 days. Several other coastal parishes and counties 

to both the east and west of Plaquemines Parish have a greater than 1.0 percent probability that they 

would be contacted by spilled oil (Table 4). The actual trajectory of the oil would depend in part on the 

prevailing meteorological conditions at the time of the spill. A large oil spill is an extremely unlikely 

event, and implementation of Shell‘s OSRP would lead to immediate response action to contain and 

collect the oil. Nevertheless, some coastal habitats to the northwest and northeast of the project area 

could be affected. Numerous national and state wildlife refuges, parks, and other protected habitats 

occur in the region potentially affected by the oil, as discussed in the Multisale and Supplemental EISs 

(MMS 2007b, 2008) and Shell‘s OSRP. If the spill continued for more than 30 days, additional coastal 

parishes and counties could be affected. 

Coastal habitat such as barrier beaches can be affected by freshly spilled oil and by weathered oil that 

arrives on shore many weeks or months after the spill. The characteristics of the oil that may appear on 

beaches would depend in part on the degree of weathering. Fresh oil is a buoyant liquid; oil mixed with 

water creates a mousse; and heavier, thicker components form tarballs (MMS 2007b). Floating oil may 

be delivered to a beach in consecutive waves, leaving a high tide line much like a wrack line. Once oil is 

deposited on the beach, it may be worked into the sand, taken up by organisms, and further weathered. 

Over time, the lighter volatile components are released to the atmosphere and the viscous remnants 

commingle with sand and shell debris to form tarball conglomerates. Some heavy oil and tar may seep 

beneath the surficial sand and appear dormant, especially when temperatures drop; tar may liquefy and 

ooze to the surface again when the sand heats up in the summer. This cycle may repeat for several 

years until the oil is completely broken down by mechanical, chemical, or microbial processes (OSAT-2 

2011; BOEM 2011a). 

The length of the recovery cycle is influenced by the chemical nature of the oil and local weather 

conditions following the deposition. Although the lighter oils typical of the northern Gulf of Mexico are 

generally prone to degradation, the breakdown products themselves can be toxic. An ongoing scientific 

debate regarding the effects of dispersants focuses on competing processes observed following the DWH 

event. By breaking up the oil slick, dispersants increase the surface to volume ratio, which promotes 

biodegradation (Atlas and Hazen 2011). However, dispersants may also retard the breakdown process by 

inhibiting bacterial metabolism (Hamdam and Fulmer 2011). Most research on dispersants assumed 

surface rather than subsea application. The role of light, nutrients, and oxygen in microbial digestion of 

oil is under active investigation (Hamdan and Fulmer 2011; Fox 2011; Atlas and Hazen 2011).

By some reports, efforts to remove oil from beaches may simply push the oil deeper below the surface. 

Mechanical removal may disturb sea turtle nests and sand-dwelling organisms, damage plants, and 
fragment habitat in ways that increase rather than decrease impacts (OSAT-2 2011; BOEM 2011a). The 

ultimate impact to beaches would depend on the particular characteristics of the spill and the post-spill 

response. 

Oil that is transported into vegetated wetland habitats is more damaging and difficult to remove than oil 

that accumulates on beaches. Wetland plants are sensitive to both the oil and the physical disturbance 

associated with removing the oil. By some estimates, a 50-bbl volume of oil in a coastal wetland would 

cause the temporary loss (die-back) of approximately 6.7 acres (2.7 hectares) of wetland vegetation. 

About a third of the damaged acreage would grow back during the first 4 years after the spill, and up to 

85 percent would have recovered within 10 years. The remainder (15 percent) of the vegetation would 

die, leaving an area of permanently open water (MMS 2007b). The recovery estimates assume no 

additional oil spills or other serious impacts occur during that period. Louisiana wetlands have 

experienced great cumulative stress that makes them less capable of recovering from significant events 

(MMS 2007b). Once a coastal marsh becomes fragmented by spatially intermittent diebacks, other forces 

such as storms can more easily break up the remaining acreage. The cumulative impacts of hurricanes 

and other stressors on marshes are discussed in Section 4.13.5. 

A large oil spill is an exceedingly unlikely event. Shell‘s approach to minimizing the risk of blowouts and 

large spills is discussed further in the Initial EP Section 2j and 9b. Shell‘s OSRP includes training, 

policies, and protocols for preventing and minimizing spills. The specific containment and collection 

procedures would vary depending on the nature of the blowout, sea state, weather, and other prevailing 

conditions. Experts in various coastal habitats would be involved in identifying the appropriate 

protection, recovery, and cleanup techniques to use in each habitat, based on the extent of the spill, the 

characteristics of the oil, the season, the perceived vulnerability of various components of the ecosystem, 

and other factors. For all these reasons, no significant impact on coastal habitat is expected to result 

from the proposed action. 

4.11 Archaeological Resources

Archaeological resources include both historic shipwrecks and prehistoric sites.

4.11.1 Shipwreck Sites

MC 525 is not in an area of high potential for historic shipwrecks, according to NTL 2005-G07 and the 

most recent list of Archaeology Survey Blocks. The Archaeological Assessment conducted by C&C 

Technologies in 2009 reported 137 unidentified sonar contacts and two debris zones located within the 

lease area. These sonar contacts were characteristic of modern debris primarily associated with industrial 

dumping or lease development activities. No shipwrecks were found within MC 525.

No historic shipwrecks are known to occur in the lease area. A small fuel or chemical spill would float 

briefly at the site and then dissipate quickly on the sea surface (NOAA 2006), without being transported 

to adjacent lease blocks where archaeological resources may occur.

The only potential IPF associated with the proposed action is a large spill that caused oil to be 

transported to adjacent lease blocks where archaeological resources occur. The BOEM requires an ROV 

survey of a 300-m (984-foot) radius around each wellsite because a severe subsurface blowout could 

resuspend and disperse sediments within that area (MMS 2007b). No shipwrecks occur within the area 

surveyed. The physical force of a blowout would not cause any direct impact to historic shipwrecks. 

If no dispersants are used to break up oil spilled in water, the oil typically rises to the surface and is then 

driven laterally by wind and surface currents and waves. Under those assumptions, a large oil spill would 

not likely affect archaeological sites on the bottom of the Gulf (MMS 2007a, 2008). The addition of 

dispersants, especially at depth, changes the behavior of the oil in ways that are not completely 

understood. Observations of the oil/dispersant mixture during the DWH event suggest that oil may 

contact shipwrecks at great depth. Subsurface plumes of oil/dispersant were reported as deep as 
3,600 feet (1,100 m) more than 22 miles (35 km) from the Macondo well for several weeks after the spill 

(Camilli and others 2010, Joint Analysis Group 2010c). Oil contacting waterlogged wood could promote 

fungal growth and accelerate the decay of the wood (Jurgens and Blanchette 2003). If dispersants were 

applied to a large oil spill, significant impacts to historical shipwrecks could occur. 

Even without the use of dispersants, a large oil spill transported to shallow water could contact 

shipwrecks. The OSRA modeling predicts that shorelines from Louisiana to Florida could be contacted by 

a spill within 30 days, although at very low probabilities (Table 4). Historic sites on or near shore, such 

as forts and lighthouses, could also be oiled, resulting in a temporary impact to visual aesthetics but no 

real harm to the structures (MMS 2007b). Once the oil was removed using safe procedures, the historic 

structures would no longer be affected by the oil.

4.11.2 Prehistoric Archaeological Sites

Prehistoric archaeological sites are not expected to occur below 197 feet (60 m) in the northern Gulf of 

Mexico. The proposed project would be in water depths of 7,400 to 7,600 feet (2,255 to 2,316 m), well 

beyond the potential range. The only potential IPF for prehistoric sites is a large oil spill that was 

transported to coastal waters, which would have similar impacts to those described above for historic 

shipwrecks. 

Numerous prehistoric sites are known on the barrier islands, mainland coast, and interior shores of bays 

and bayous all along the northern Gulf of Mexico (MMS 2007b), including areas that could receive oil that 

was transported to the coast after a large offshore spill (Table 4). Oil that reaches prehistoric sites could 

physically cover important artifacts, contaminate delicate materials, and interfere with radiocarbon dating 

(because the fresh organic hydrocarbons would yield a false signal of age). Although this type of oil 

contact can be cleaned, the removal process itself can physically damage fragile materials and settings of 

archaeological importance.

A large oil spill is exceedingly unlikely to occur or to cause any significant impact beyond the immediate 

project area. Shell‘s approach to minimizing the risk of blowouts and large spills is discussed further in 

the Initial EP Section 9b. Shell‘s OSRP includes training, policies, and protocols for preventing spills. 

The specific containment and collection procedures would vary depending on the nature of the blowout, 

location (nearshore or offshore), sea state, weather, and other immediate conditions. Impacts to shallow 

water shipwrecks or nearshore prehistoric sites are not expected to result from the proposed action. 

4.12 Socioeconomic and Other Resources

Principal socioeconomic concerns in the northern Gulf of Mexico, aside from oil and gas production, 

include recreational and commercial fishing; non-fishing recreation and tourism; and coastal employment 

and infrastructure. Other concerns addressed in this section include public health and safety, land use, 

and other marine uses.

4.12.1 Recreational and Commercial Fishing

Recreational fishing in the Gulf of Mexico is a $12 billion industry, including manufacturing, retail sales, 

charter operations, fishing guides, and license fees; sales of durable equipment accounted for most of the 

total. More than 100,000 jobs in the Gulf states were supported by the recreational fishing industry in 

2008 (National Ocean Service [NOS] 2008). About 24 million recreational fishing trips were taken in the 

Gulf of Mexico in 2008, representing almost 30 percent of the national total (NOS 2008).

Almost 50 percent of the total recreational catch in the Gulf of Mexico was a single species, spotted 

seatrout (Cynoscion nebulosus). Other important recreational species include Atlantic croaker 

(Micropogonius undulatus), southern flounder (Paralichthys lethostigma), Gulf and southern kingfish 

(Menticirrhus littoralis), sand and silver seatrout (Cynoscion arenarius and C. nothus), red drum (Scianops 

ocellatus), Spanish mackerel (Scomberomorus maculatus), striped mullet (Mugil cephalus), sheepshead 

(Archosargus probatocephalus), and red snapper (Lutjanus campechanus). Most of these species are 
caught in coastal waters and shallow bays, often associated with oyster beds, marsh vegetation, and tidal 

inlets of state waters. The habitat function of platforms as artificial reefs is well-known and forms the 

basis of the ―Rigs to Reefs‖ programs in the Gulf. However, offshore trips to oil and gas platforms make 

up a small percentage of recreational fishing excursions (BOEM 2010b). No recreational or commercial 

fishing is allowed from the drillship or support vessels associated with the proposed action. 

Commercial fishing ports in the northern Gulf of Mexico produced almost 1.3 billion pounds of fish and 

shellfish in 2008. The catch was worth more than $650 million; shellfish accounting for more than 75 

percent of the value (NMFS 2010d). Revenues for finfish and shellfish generally declined between 1999 

and 2008 (NMFS 2010d). About 200,000 jobs are sustained by the commercial fishing industry across 

the five Gulf states (NMFS 2010d). The top commercial species in the Gulf of Mexico are blue crab 

(Callinectes sapidus), mullet, stone crab (Menippe mercenaria), oyster (Crassostrea virginica), brown 

shrimp (Farfantepenaeus aztecus), white shrimp (Litopenaeus setiferus), groupers (Family Serranidae), 

red snapper, menhaden (Brevoortia patronus), and tunas (Thunnus spp.). Other than the tunas, these 

commercially important species occur in shallower waters shoreward of the project area. 

The only commercial fishery active in the immediate project area is for tuna and swordfish by longlines. 

About 50 longline fishing vessels harvest yellowfin tuna and swordfish with an annual dockside value of 

$7 million (NMFS 2011b). Longlining occurs in the immediate project area as well as over a broad swath 

of the northern Gulf of Mexico (Teo and Block 2010). 

Routine IPFs associated with the proposed action would not affect commercial or recreational fishing, nor 

would a small fuel or chemical spill. However, a large oil spill could directly affect important fisheries 

species or lead to fisheries closures, which could result in economic impacts. 

Impacts of a Large Oil Spill on Fishing

The impacts of an oil spill on the complex array of fisheries activities in the Gulf of Mexico has been 

analyzed in regional Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a). Nothing in the 

proposed action would change the conclusions of those EISs, which are incorporated by reference into 

this EIA. Depending on the time of year, the duration of the spill, the use of dispersants, and the 

prevailing meteorological conditions during and immediately after the spill, a substantial portion of the 

offshore waters of the northern Gulf of Mexico could be temporarily affected. More severe impacts to 

economically important fisheries species would be expected in areas where the oil enters shallower water 

and reaches the shoreline. Extensive fisheries closures after the DWH event caused some short-term 

economic impacts. The closures covered 84,101 mi2(217,821 km2), or about 35 percent of the U.S. EEZ 

in the Gulf of Mexico (NMFS 2010e), but did not necessarily cause permanent harm to any fisheries. In 

fact, closures are widely used as management tools to create an opportunity for fisheries stocks to 

rebound, and are thought to have protected some spawning stocks following the DWH event (Fodrie and 

Heck 2011). 

The DWH event in 2010 resulted from a unique series of events that is extremely unlikely to recur. In 

response to that event, Shell has joined with other entities to develop more rigorous and effective 

blowout prevention devices and procedures to minimize the likelihood of a similar large spill (see Shell‘s 

OSRP and Initial EP Sections 2j and 9b). BOEM has implemented extensive programmatic reforms to 

enhance safety and ensure that operators are equipped to respond to accidents. Because of Shell‘s 

commitment to prevention and containment of spills, a large spill is not expected to cause significant 

long-term adverse impacts on recreational or commercial fishing in the northern Gulf of Mexico. 

4.12.2 Non-Fishing Recreation and Tourism

The project area is not used for any recreational activities. No routine IPFs associated with the proposed 

action would affect recreation or tourism because the lease block is 79 miles (127 km) from shore. Shell 

complies with all waste disposal regulations, including NTL 2007-G03, which minimizes the loss of debris 
from the drillship and support vessels that might be deposited in coastal recreational or tourism sites. 

Small fuel or chemical spills would be localized and short-lived, as described in Section 4.2.2 (NOAA 

2006). No significant impacts to non-fishing recreation or tourism would occur.

A large oil spill could adversely affect non-fishing recreation and tourism across the Gulf coast, as 

described in the regional Multisale and Supplemental EISs (MMS 2007b, 2008). The proposed action 

does not add any unique IPFs that would require a separate analysis of the impacts. The impacts on 

recreation and tourism are similar to those described in Section 4.10.2 for coastal habitats. Most 

recreation and tourism on the Gulf coast are tied directly or indirectly to the Gulf itself or to the shoreline. 

A blowout could release a substantial volume of oil into the Gulf that could contact and contaminate 

coastal recreational areas such as beaches, parks, and boat docks. Non-fishing recreation centered on 

wetlands, such as duck hunting, could be affected by oil in coastal marshes (MMS 2007b 2008). 

The most likely area to be contacted by spilled oil is Plaquemines Parish, Louisiana, according to the 

OSRA model. Several other coastal parishes and counties both east and west of Plaquemines Parish have 

a greater than 1.0 percent probability that they would be contacted by oil after the spill (Table 4). The 

actual trajectory of the oil would depend in part on the prevailing meteorological conditions at the time of 

the spill. A large oil spill is an extremely unlikely event, and implementation of Shell‘s OSRP would lead 

to immediate response action to contain and collect the oil. Nevertheless, some coastal recreational 

areas from Texas to Florida could be affected. Numerous national and state wildlife refuges, parks, and 

other recreational destinations occur in the region potentially affected by a large spill, as discussed in the 

Multisale and Supplemental EISs (MMS 2007b, 2008) and Shell‘s OSRP. If the spill continued for more 

than 30 days, additional tourism and recreational locations in coastal parishes and counties could be 

affected. 

The duration of the impacts to tourism and recreation from a large oil spill is difficult to predict. During 

the DWH event, some recreation and tourism declined in locations where no oil contact occurred, or in 

advance of the oil‘s arrival. Media attention, uncertainty, and misinformation can cause people to cancel 

plans for recreation, leading to a cascade of loss of tourism revenue, including hotels, car rentals, 

restaurants, and retail sales.

Recreational areas and facilities on the coast may be affected by freshly spilled oil and by weathered oil 

that arrives onshore many weeks or months after the spill, as described in Section 4.10.2 for coastal 

habitats. The same processes and effects described as impacts to coastal habitats for wildlife are 

considered impacts to the human population using the oiled area. 

Oil that is transported into vegetated wetland habitats is more damaging and difficult to remove than oil 

that accumulates on beaches, as described in Section 4.10.2. Non-fishing recreation in coastal marshes, 

such as duck hunting, could be temporarily affected by actual or perceived degradation of the marsh. 

Hunters could go elsewhere to avoid the degraded areas or cancel their trips altogether. If the oiled 

areas suffer permanent loss of vegetation, non-fishing recreation also would decline (MMS 2007b). 

A large oil spill is an exceedingly unlikely event. Shell‘s approach to minimizing the risk of blowouts and 

large spills is discussed further in the Initial EP Section 2j and 9b. Shell‘s OSRP includes training, 

policies, and protocols for preventing and minimizing spills. The specific containment and collection 

procedures would vary depending on the nature of the blowout, location, sea state, weather, and other 

prevailing conditions. Experts in various coastal habitats would be involved in identifying the appropriate 

protection, recovery, and cleanup techniques to use in each habitat, based on the extent of the spill, 

characteristics of the oil, season, perceived vulnerability of various components of the ecosystem, and 

other factors. For all these reasons, no significant long-term impact on recreation or tourism is expected 

to result from the proposed action. 
The immediate local economic effects on individual recreational or tourist facilities would be exacerbated 

by larger-scale regional problems with the image of the Gulf coast as a desirable tourist destination. 

Market studies conducted during and after the DWH event indicated that the public may be hesitant to 

accept that it is safe to swim and eat seafood caught in the Gulf of Mexico (Innovative Emergency 

Management, Inc. (IEM) 2010, Oxford Economics 2010; Gohlke and others 2011). The Gulf Coast was 

predicted to suffer economic losses of almost $23 billion during the 3 years after the DWH event, largely 

the result of diminished public interest in visiting there (Oxford Economics 2010). However, the regional 

recreational economy has recovered more quickly than expected. Hotels, restaurants, and recreational 

facilities have reported full occupancy. In fact, the Mississippi's Gulf Coast reported that 2011 occupancy 

was the highest in 3 years (Myers 2011). Florida‘s 2011 coastal tourism business increased by 3.3 

percent compared with the same pre-spill period in 2010 (Myers 2011). In a recent SEA that evaluated 

exploratory activities similar to the proposed action, impacts to socioeconomic factors such as recreation 

and tourism were deemed negligible (BOEM 2011b). Likewise, no significant long-term irreversible 

adverse impact to recreation or tourism would result from the proposed action. 

4.12.3 Coastal Employment and Infrastructure

The OCS oil and gas industry supports a wide variety of people who move among various projects as 

needed. None of the routine IPFs associated with the proposed action would directly affect employment 

or infrastructure. The supply and support vessels proposed for this project already exist and are serving 

other OCS projects in the area. The proposed action would use existing shore-based facilities in 

Louisiana and not require any expansion of infrastructure or increase in personnel. The project would 

have a negligible impact on employment and infrastructure. The project would not raise any concerns 

with environmental justice because it would not disproportionately affect minority or lower-income 

groups. 

The only IPF associated with the proposed action that could significantly affect employment is a blowout 

that results in a large oil spill that interrupted the normal flow of work offshore. The potential 

socioeconomic impacts of a major spill are discussed in regional Multisale and Supplemental EISs (MMS 

2007b, 2008; BOEM 2011a). The proposed action does not include any unique or unusual activities that 

would change the assumptions or predictions of the regional EISs. 

A large oil spill could cause major temporary direct and indirect economic impacts by interrupting the 

income flow of people who work in the oil and gas, commercial fishing, charter boat, and coastal tourism 

industries. Some individuals may be able to switch to short-term work in support of the response effort, 

but this switch is not considered complete compensation for the loss of a person‘s chosen livelihood. 

People in coastal communities directly affected by a large spill would be directly impacted by lost income. 

In addition, people in communities beyond the reach of the oil spill may experience indirect economic 

impacts that require them to reevaluate their spending habits and change the way they allocate 

resources on both an individual and community level as income sources are diverted toward oil response 

and cleanup (Grattan and others 2011). 

The severity of the economic losses would depend on the duration of the fishing closures and drilling 

suspensions; the extent of public hesitation in returning to recreation and tourism in the area; and a 

variety of other unpredictable variables, such as decisions of individuals to return to former types of work 

after the spill. 

The proposed action is extremely unlikely to result in a large oil spill. Shell‘s well control and blowout 

prevention measures would minimize the probability of any significant long-term impact on employment 

resulting from a spill. (See Initial EP Sections 2j and 9b for additional details on Shell‘s policies and 

procedures designed to protect against a blowout and accidental release of oil.) The combined effects of 

distance of the well sites from shore and Shell‘s rigorous OSRP support the conclusion that no significant 

impacts on employment or infrastructure would result from the proposed action.
4.12.4 Public Health and Safety

The only people potentially exposed to routine IPFs associated with the proposed action are trained 

personnel who are performing specific tasks necessary to do their jobs. The public is not exposed to any 

activities that occur on the drillship. The supply vessels and helicopters are operated by licensed 

professionals who are contracted to fulfill certain functions and are not modes of public transportation. 

The drillship is more than 79 miles (127 km) from a point of public exposure. Vessel crews are trained 

and equipped to respond to small fuel or chemical spills and would not experience any ill effects. No 

routine activities or small spills would be expected to affect public health or safety. 

In the unlikely event that a blowout and large oil spill did occur, first responders could experience 

compromised safety and health for a short period of time (Levy and Nasetta 2011; Solomon and Janssen 

2010). Shell‘s OSRP provides comprehensive plans for protecting the people who are responsible for 

stemming the flow of oil and containing the oil that is released. Shell‘s OSRP meets or exceeds safety 

requirements set forth by USCG, EPA, the Occupational Safety and Health Administration (OSHA), and 

the International Convention for the Prevention of Pollution from Ships (MARPOL).

One of the principal goals of the first responders is to protect the health and safety of the public on shore 

by minimizing the amount of oil that arrives on the coast and the length of time it remains there. Shell‘s 

OSRP includes descriptions of several potential scenarios as guides, but the actual response methods 

would depend on the specific circumstances of the spill (flow rate, use of dispersants, characteristics of 

the oil, meteorological conditions during and after the spill, whether the oil was burned [intentionally or 

accidentally], and other variables). 

If liquid oil or smoke and fumes from burning oil reaches coastal communities, some people on the 

shoreline could be adversely affected (USCG 2009). Dermal exposure to oil could result from people 

walking through oiled areas and picking up oiled objects (including wildlife). People could be exposed via 

inhalation to volatile components of the oil as it weathers, to gases such as methane released with the 

oil, and to smoke and fumes from burning oil. Finally, people may ingest oil either incidentally as they 

work around contaminated materials or as part of their food. 

The National Institute for Occupational Safety and Health (NIOSH) evaluated the effects of human 

exposure to oil spilled during the DWH event. Although the final health hazard evaluation has not been 

released, some preliminary conclusions have been reported (Centers for Disease Control and Prevention 

[CDC] 2010a, b; Levy and Nasetta 2011). People exposed directly to oil while rescuing and cleaning 

wildlife reported symptoms consistent with dermal and inhalation exposure to oil, including red itchy skin, 

headache, lightheadedness, and fatigue. Crew members on vessels reported upper respiratory distress 

such as nose irritation, coughing, and sore throat. Headaches and heat-related stress were also 

commonly reported. 

Some indirect health-related impacts on spill-response workers were suspected but not confirmed, such 

as increased respiratory viruses caused by the close living quarters, respiratory irritation caused by dust 

and gravel at the docks, and second-hand smoke (CDC 2010b). These symptoms are consistent with 

health effects reported by people exposed to 38 other large oil spills worldwide (Levy and Nasetta 2011). 

In addition to the physiological symptoms experienced by response workers, people across the Gulf coast 

reported psychological effects stemming from lost income and security after the DWH event (Grattan and 

others 2011). Researchers predict that the long-term impact of the DWH event and by extension, any 

large oil spill, will be the psychological stress of job loss and subsequent failure to cope (Reardon 2011).

The proposed action is in an area known where H2S concentrations have not been characterized. 

Unanticipated exposure to H2S could occur during a response action. During the DWH event, some 

response workers reported heat-related stresses. If a large spill occurred during cooler months, both 

inhalation exposure and heat-related stresses would likely be reduced, but hypothermia could pose a risk. 

A large oil spill is an extremely unlikely event. Shell‘s well control and blowout prevention measures 

would minimize the probability of a large spill, as described in Initial EP Section 2j and 9b. No 
significant impacts on public health or safety would result from the proposed action because the project 

area is 79 miles (127 km) from the nearest shoreline where land use is an issue and Shell has committed 

to a rigorous OSRP focused on minimizing the chance of a blowout.

4.12.5 Land Use

Land use along the northern Gulf coast is determined largely by its function in the coastal economy. 

Support facilities for the offshore oil and gas industry are aggregated in Louisiana coastal parishes 

(notably Lafourche and Plaquemines). Often the same local areas, and even many of the same 

individuals, are committed to both the oil and gas and fisheries industries. The proposed action is typical 

of the type of project that supports existing land uses on the Louisiana coast where the supply bases are 

located. 

Regional Multilsale EISs analyzed the potential for deepwater oil and gas development to adversely affect 

land use and concluded that no impact was likely (MMS 2007b, 2008). No routine IPFs are expected to 

affect land use. Existing onshore industrial support facilities in Louisiana would be used, and no 

expansion of land-based facilities would be required. 

The only potential IPF affecting land use is large oil spill, which could produce temporary changes in land 

use in limited areas. For example, a major oil spill requires staging areas for the response team, 

expansion of parking and boat docking areas, additional disposal areas for cleanup wastes, temporary 

lodging for response personnel, and other short-term localized adjustments to typical land use. The 

baseline land use would be restored as the number of people actively responding to the spill decreases 

over time. The only permanent change in land use could be additional disposal areas, but these areas 

are permitted by a separate municipal process that is independent of the proposed action. 

Changes in land use are not expected to occur because a large oil spill is an extremely unlikely event. 

Shell‘s well control and blowout prevention measures would minimize the probability of a spill, as 

described in Initial EP Section 2j and 9b. No significant impacts on land use would result from the 

proposed action because the project area is 79 miles (127 km) from the nearest shoreline where land use 

is an issue and Shell has committed to a rigorous OSRP focused on minimizing the chance of a blowout.

4.12.6 Other Marine Uses

The lease block (MC 525) is not in the ―Military Warning and Water Test Areas,‖ subject to NTL 2009-G06 

and is not typically used for military testing or training. Shell would comply with BOEM requirements and 

lease stipulations to avoid conflicts with military vessels and aircraft. No subsea wells or flowlines occur 

in the vicinity of the proposed wellsite locations. The DP drillship will not use anchors or mooring lines. 

No routine IPFs associated with the proposed action would affect shipping or other marine uses. A large 

oil spill could cause a temporary interruption of shipping in the immediate area if a fire or other event 

made it unsafe for vessels to transit through the area. However, the lease is in a wide open area of the 

Gulf outside shipping lanes designated by the USCG; vessels would be expected to simply navigate 

around the site if necessary. In the event that a large aggregation of response vessels caused a 

navigational hazard, USCG would manage vessel traffic in a safe and orderly manner. 

Shell does not anticipate any loss of well control that would lead to a large oil spill. Shell‘s blowout 

prevention technology and procedures would minimize the probability of a large spill, as described in 

Initial EP Section 2j and 9b. No significant impacts on other marine uses would result from the 

proposed action because Shell has committed to a rigorous OSRP focused on minimizing the chance of a 

blowout and has highly trained personnel in place to respond to an accident at the site.
Table 11. Summary of Effects of the Proposed Action on Protected and Managed Resources

Protected Resources

Physical Presence of 

Drillship and Vessels 

(Noise/Lights)

Water 

Intake Effluent

Air 

Emissions Wastes

Small Fuel or 

Chemical 

Spill

Vessel Strikes

(boats and 

helicopters)

Large 

Oil Spill 

Air Quality ○ ○ ○ ◊ ○ ◊ ○ ■

Water Quality ○ ○ ◊ ○ ○ ◊ ○ ■

Marine Species

Deepwater Benthic 

Communities

○ ○ ◊ ○ ○ ○ ○ ■

Lower Trophic 

Levels

○ ○ ◊ ○ ○ ◊ ○ ■

Fish ◊ ◊ ◊ ○ ○ ◊ ◊ ■

Sea Turtles ◊ ○ ◊ ○ ○ ◊ ◊ ■

Birds ◊ ○ ○ ◊ ○ ◊ ◊ ■

Marine Mammals ◊ ○ ◊ ○ ○ ◊ ◊ ■

Coastal Species

Diamondback 

Terrapin

○ ○ ○ ○ ○ ◊ ○

○

■

Beach Mouse ○ ○ ○ ○ ○ ◊ ○ ■

Coastal Habitats ○ ○ ○ ○ ○ ◊ ○ ■

Archeological Resources

Shipwrecks ○ ○ ○ ○ ○ ○ ○ ■

Prehistoric Sites ○ ○ ○ ○ ○ ○ ○ ■

Socioeconomic Resources

Recreational and 

Commercial Fishing

◊ ○ ○ ○ ○ ◊ ○

○

○

■

Non-fishing 

Recreation

○ ○ ○ ○ ○ ◊ ○ ■

Employment ○ ○ ○ ○ ○ ○ ○ ■

Land Use ○ ○ ○ ○ ○ ○ ○ ■

Other Marine Uses ○ ○ ○ ○ ○ ○ ○ ■

Note: The symbol in each cell represents the maximum potential effect level for the proposed action described in the text. 

Key:

○ No effect ◊ May affect, not likely to adversely affect ■ Likely to adversely affect
4.13 Cumulative Impacts

Cumulative impacts are the additive consequences of the proposed action and other unrelated events 

reasonably expected to occur in the action area.

The U.S. Council on Environmental Quality defines ―cumulative effects‖ (also called ―cumulative impacts‖ 

in NEPA documents) as follows: ―the impact on the environment which results from the incremental 

impact of the action when added to other past, present, and reasonably foreseeable future actions 

regardless of what agency (Federal or non-federal) or person undertakes such other actions‖ (40 CFR 

1508.7). The analysis of cumulative impacts in this EIA focuses on the incremental impact that the 

proposed action would (or could) have in combination with natural and anthropogenic stressors on 

important resources in the action area. Cumulative impacts can result from individually minor but 

collectively significant actions that take place over a period of time. Pre-existing impacts of activities that 

have already occurred are not explicitly included in the cumulative impacts analysis, but are reflected in 

the descriptions of the affected environment (Section 4.0). Impacts from prior activities that are still 

ongoing are considered current impacts and are discussed in this section. The cumulative impacts of the 

proposed action are the sum of previous, current, and proposed direct and indirect impacts of natural and 

human activities on a given resource.

The following types of cumulative impacts were examined with respect to the proposed action:

Additive effects, where individual effects from actions additively affect the same environmental 

resources;

Countervailing effects, where the total cumulative effect is less than the sum of individual effects; or

Synergistic, where the total cumulative effect is greater than the sum of the individual effects.

Given the uncertainties, complexities, and limited data availability associated with a large spill, the 

cumulative impacts of the proposed action cannot be quantitatively estimated. The discussion of 

cumulative impacts incorporates by reference the extensive analyses in the Multisale and Supplemental 

EISs (MMS 2007b, 2008; BOEM 2011a) and in the site-specific SEA S-7445 (BOEM 2011b) prepared after 

the DWH event.

Before MC 525 was offered for lease (in Lease Sale 205 on October 3, 2007), MMS prepared a 

programmatic EIS that analyzed the cumulative impacts of Lease Sale 205 in the context of other OCS 

and related activity (MMS 2007b). The proposed action is well-represented by the range of activities 

analyzed in that EIS, as described below: 

―environmental and socioeconomic impacts that may result from the incremental impact of 

the lease sales when added to all past, present, and reasonably foreseeable future human 

activities, including non-OCS activities such as import tankering and commercial fishing, as 

well as all OCS activities (OCS Program). The OCS Program scenario includes all activities 

that are projected to occur from past, proposed, and future lease sales during the 40-year 

analysis period (2007-2046). This includes projected activity from lease sales that have 

been held, including the most recent Lease Sale 200 (August 2006), but for which 

exploration or development has not yet begun or is continuing. In addition to human 

activities, impacts from natural occurrences, such as hurricanes, are analyzed."

Cumulative impacts were analyzed again in 2008 when MMS prepared an SEIS for additional lease blocks 

in the Central Planning Area (MMS 2008). The activities included in the proposed action clearly fall within 

the cumulative analysis presented in MMS (2007b). 
Activities described in the Initial EP were considered as part of the multiple lease sales along with impacts 

related to fishing, hurricanes, and other events that could occur during the 40-year leasing period (2007 

to 2046) (MMS 2007b). Impacts associated with the lease sales included exploration (the current 

proposed action), as well as delineation and development wells and platforms. The cumulative impacts 

of support vessels, small fuel spills, and major oil spills were included in the regional analysis. The 

proposed action does not include any activity that would alter the conclusions of the Multisale and 

Supplemental EISs. 

The project area is in a region of the Gulf of Mexico with a history of extensive oil and gas exploration 

and development that can reasonably be expected to continue. Shell is conducting exploration and 

development in adjacent and nearby areas, in accordance with BOEM regulations. 

This EIA provides site-specific information that allows a focused comparison of the proposed plan with 

the activities analyzed in the regional EISs. The Initial EP described activities that are consistent with 

activities described and evaluated in the Multisale EISs. This EIA incorporates details of the well locations 

and drillship and provides a calculated WCD based on methods prescribed in NTL 2010-N06. The 

analysis relies in part on new data collected since the DWH event, although much of the spill-related data 

are not yet publicly available. Although the DWH event illustrated the ways in which a major oil spill 

could affect various resources in the Gulf of Mexico, it also elicited changes in the way the industry 

prepares for and prevents these accidents. Shell is better prepared to respond to a spill now than it was 

before the DWH event. Moreover, BOEM has provided comprehensive guidance to improve the safety of 

drilling in deep water. The combined efforts of BOEM and Shell have resulted in an unprecedented set of 

policies and procedures for preventing a blowout and minimizing an unplanned release from a well, as 

described in Shell‘s Initial EP and OSRP. The net result of these efforts is that the proposed action would 

not significantly increase the cumulative impacts on any environmental, archaeological, or socioeconomic 

resource. 

Greenhouse Gases and Climate Change

GHG emissions occur from natural processes and human activities. The accumulation of greenhouse 

gases in the atmosphere regulates the earth‘s temperature and may contribute to global climate change, 

including rises in sea surface temperature, sea level, ocean acidification, and severe weather. Climate 

change may affect physical and biological resources in the project area in numerous ways, including loss 

of calcification of hard corals, increased vulnerability of coastal wetlands as sea level rises, and 

intensification of tropical storms and hurricanes resulting from higher sea surface temperatures. 

In the EIS for the Outer Continental Shelf Oil & Gas Leasing Program: 2007-2012 (MMS 2007a), the 2007 

to 2012 leasing program was reported to make a negligible contribution to the global concentrations of 

GHG. However, since the programmatic EISs for the Central Planning Area were prepared in 2007, CEQ 

and EPA have increased attention on the generation of GHG. Impacts of GHG on climate change are 

more commonly being included in NEPA analyses. Although not formally required by CEQ, federal courts 

have concluded that GHG emissions are ―a reasonably foreseeable consequence‖ of agency actions that 

must be included in NEPA analyses (Till and Brandt-Erichsen 2010). Federal agencies are, on a national 

scale, addressing emissions of greenhouse gases by reductions mandated in federal laws and Executive 

Orders, most recently, Executive Order 13423.

EPA predicts that GHG emissions from most anthropogenic sources will continue to increase (EPA 2011c), 

but acknowledges that multiple unpredictable factors contribute to the rate of GHG production. The 

effects of increased GHG production are long-term and complex. BOEM (2011a) estimated that relative 

sea level in the northern Gulf of Mexico will rise about 18 inches (45 cm) over the next 40 years, based 

on a rate of approximately 0.35 inch [9 mm]/yr. The change in sea level is partially attributed to 

subsidence (about 0.23 in [6 mm]/yr) and partially to climate change (BOEM 2011a). 
Attention is now focused on the effects of acidification of the oceans, as excess atmospheric CO2 is being 

dissolved in the sea. Ocean acidification is considered a global threat to marine ecosystems. Ocean 

acidification is the reduction of pH of seawater, which decreases the concentration of the carbonate ion in 

seawater. Coastal habitats are considered especially vulnerable to acidification, as they are expected to 

experience both increases in sea temperature and decreases in pH (Teck and others 2010).

The potential effects of GHG emissions from the proposed action are by nature incremental. The 

incremental contribution of the proposed action is minimal as individual sources of greenhouse gas 

emissions are not large enough alone to have an appreciable effect on climate change. Shell is 

committed to reduce the impacts of its operations on climate change by increasing the production of 

clean-burning natural gas, investing in sustainable biofuels; working on innovative methods for capturing 

and storing CO2 emissions; and increasing the energy efficiency of its global operations (Shell 2011). In 

2010, Shell met a voluntary target set in 1998 for direct greenhouse gas emissions from its facilities to be 

at least 5% lower than the comparable 1990 level (Shell 2011). 

Other Cumulative Impacts

Cumulative impacts resulting from the following activities, unrelated to the proposed action, were 

analyzed in the WPA SEIS (BOEM 2011a, Section 3.3), and are incorporated by reference:

 State oil and gas activity and pipeline infrastructure

 Other major factors Influencing offshore environments

o Dredge material disposal

o OCS sand borrowing

o Marine transportation

o Military activities

o Artificial reefs and rigs-to-reefs development

o Offshore liquefied natural gas projects and deepwater ports

o Development of gas hydrates

o Renewable energy and alternative use

 Other major factors influencing coastal environments

o Sea-level rise and subsidence

o Formation extraction and subsidence

o Mississippi River hydromodification

o Maintenance dredging and navigation channels

o Coastal restoration programs

o Coastal Impact Assistance Program

o Gulf Coast Ecosystem Restoration Task Force

 Natural events or processes

o Hurricanes

o Currents as transport agents

4.13.1 Cumulative Impacts to Air Quality

Cumulative impacts to air quality include emissions from both onshore and offshore sources. Onshore 

sources originate from power generation, industrial processing, manufacturing, refineries, commercial 

and home heating, and motor vehicles (MMS 2007b). Offshore emissions, which are dominated by 

marine vessels, have increased in recent years. In 1996, Compression-Ignition (CI) marine engines were 

responsible for 7 percent of the total mobile source NOx emissions in the United States, 6 percent of total 

mobile source PM2.5 emissions, and 21 percent of total mobile source SO2 emissions. The EPA predicts 

that by 2030, marine engines will contribute 25 percent of mobile NOx emissions, 25 percent of PM2.5 

emissions, and 81 percent of mobile SO2 emissions (Fournier, 2006). In addition, shipping operations are 

responsible for 2.7 percent of global carbon dioxide CO2) emissions. In the absence of policies to curb 

greenhouse gas (GHG) emissions, the International Maritime Organization (IMO)estimates by 2050 that 

the CO2 emissions may grow by a factor of 2 to 3 as a result of growth in shipping (IMO 2009).
Recent federal short-term NAAQS for NO2 and SO2 emissions may serve as countervailing impacts to 

offset the increased emissions generated by coastal population growth. In general, activities associated 

with offshore exploration in deep water are not considered to contribute significantly to air quality 

impacts (see Section 4.1) (MMS 2007b; BOEM 2011a). The proposed action would not contribute 

significantly to degradation of air quality in the region. 

4.13.2 Cumulative Impacts to Water Quality

Cumulative impacts to water quality are heavily influenced by onshore processes, especially urban runoff 

(BOEM 2011a). Water quality may be degraded by suspended solids, heavy metals and pesticides, oil 

and grease, and nutrients, which are generally released in proportion to coastal population size. As the 

human population of the Gulf states continues to grow, urban runoff is expected to increase (NOS 2008). 

Coastal and offshore water quality is also affected by agricultural runoff, municipal and industrial point 

sources, dredging and dredge disposal, and vessel-related discharges. 

The National Estuary Program‘s Coastal Condition Report (EPA 2007) reported that U.S. coastal waters 

are in ―fair to good‖ condition. More than half (57 percent) of the coastal areas were rated ―good‖ for 

water quality; about a third (34 percent) were rated ―fair,‖ and only 6 percent were considered ―poor.‖ 

Water quality has improved substantially overall since the initial survey in 2001, reflecting concerted 

efforts to reverse the degradation noted at that time. The Gulf Coast scored 3 out of 5 on overall water 

quality. The principal cause of degraded water quality across all U.S. coasts is loss of water clarity 

(increased turbidity) and excess nutrients leading to increased chlorophyll a (EPA 2007).

Healthy aquatic and marine ecosystems are characterized by oxygen concentrations of at least 2 to 3 

milligrams of oxygen per liter of water (mg/L). Some organisms require even higher levels of dissolved 

oxygen, up to 4.5 mg/L. Water with less than 2.0 mg/L dissolved oxygen is called ―hypoxic‖ (CENR 

2010). The largest hypoxic zone currently affecting the United States, and the second largest hypoxic 

zone worldwide, occurs in the northern Gulf of Mexico adjacent to the Mississippi River on the 

Louisiana/Texas continental shelf. The hypoxic zone in the northern Gulf of Mexico from 2004 to 2008 

averaged about 6,563.7 mi2(17,000 km2), about a third again as large as the surface area of the 

Chesapeake Bay and all its major tributaries (Louisiana Universities Marine Consortium [LUMCON] 2010). 

Hypoxic zones, often called ―dead zones,‖ support very little life other than bacteria. 

Offshore waters in the lease area are not expected to be degraded by onshore pollutants to any great 

extent, but they are subject to increases in water temperature and acidification. The small amount of 

discharge anticipated under the proposed action would add a negligible amount of turbidity to the 

immediate vicinity of the wellbore and would have no effect on hypoxia, turbidity, or nutrients. Based on 

data from the DWH event, even a large oil spill would not contribute substantially to the cumulative 

impacts of all activities on water quality in the Gulf of Mexico. The proposed action would not contribute 

significantly to water quality impacts in the region. 

4.13.3 Cumulative Impacts to Marine Species and Habitats

Cumulative impacts to deepwater benthic communities, lower trophic level organisms, fish and EFH, sea 

turtles, coastal and marine birds, and marine mammals are discussed below.

4.13.3.1 Cumulative Impacts to Deepwater Benthic Communities

Both chemosynthetic and nonchemosynthetic deepwater benthic communities are thought to be affected 

by global changes in ocean temperature and pH. As seawater becomes acidic, animals that use the 

carbonate ion to build hard structures, such as corals, experience a reduction or cessation of growth 

(Manzello 2010). Loss of structure-forming coral reefs leads to a cascade of habitat degradation that 

threatens entire ecosystems (Lubchenco and Petes 2010). Additional threats to deepwater benthic 

communities include bottom trawling, carbonate mining, and hypoxia (Cordes and others 2009; CENR 

2010). The proposed action would not contribute significantly to impacts on deepwater communities 

because it would not add substantially to GHG or physically impact extensive areas of deepwater habitat. 
4.13.3.2 Cumulative Impacts to Lower Trophic Levels

No human activities are reasonably expected to cause significant impacts to lower trophic level organisms 

in the northern Gulf of Mexico. The area is so vast and well-mixed that these planktonic communities are 

not at risk of local decline. Global sea temperature change and acidification could cause shifts in species 

assemblages over time, but no aspect of the proposed action would contribute to such changes. 

4.13.3.3 Cumulative Impacts to Fish, Fisheries, and EFH

Stressors on marine fishes that contribute to cumulative impacts in the northern Gulf of Mexico include 

overfishing, pollution, and nonnative species (discussed below). Climate change, aquaculture, energy 

production, and underwater noise are of concern globally but are of secondary importance in the project 

area. 

Overfishing is the most important threat that has led to the listing of ESA-protected marine species 

(Kappel 2005; Crain and others 2009) with habitat loss also contributing to extinction risk. Approximately 

30 percent of the United States-managed fishery stocks are overfished (NMFS 2009c). Overfishing occurs 

when fishes are harvested in quantities above a sustainable level. 

Pollution primarily impacts coastal fishes that occur near the sources of urban runoff. However, global 

oceanic circulation patterns result in a considerable amount of marine pollutants and debris scattered 

throughout the open ocean (Crain and others 2009). Pollutants in the marine environment that may 

affect marine fishes include organic pollutants (such as pesticides, herbicides, polycyclic aromatic 

hydrocarbons, flame retardants, and oil), inorganic pollutants (for example, heavy metals), and debris 

(plastics and wastes from dumping at sea) (Pew Oceans Commission 2003). 

Fisheries managers in the Gulf of Mexico are concerned about the impacts of invasive species in the Gulf 

of Mexico. Lionfish (Pterois volitans and P. miles), native to the Pacific Ocean, are spreading rapidly 

throughout the Gulf of Mexico. These predaceous fishes were first observed at the Flower Garden Banks 

National Marine Sanctuary (FGBNMS) in summer 2011 and are expected to affect native invertebrates 

and fishes there as they have been reported to do in the southeast Atlantic (FGBNMS 2011). Another 

invasive species, the Australian spotted jellyfish (Phyllorhiza punctata), appeared by the thousands in the 

Gulf of Mexico in the summer of 2000 and again in 2003 (U. S. Geological Survey 2009). The biomass of 

jellyfish was so great that it clogged shrimp trawls, damaged the engine intakes on boats, and entangled 

fishing gear, resulting in the closure of otherwise productive fishing areas (USGS 2009). The jellyfish 

may also indirectly degrade commercial and recreational fisheries by eating the larval fishes that form the 

prey base for economically important fishes. The proposed action would not contribute significantly to 

cumulative impacts on fish, fisheries, or essential fish habitat. 

4.13.3.4 Cumulative Impacts to Sea Turtles

Sea turtles are threatened both onshore during nesting and hatching and offshore as juveniles and 

adults. Two of the greatest threats to sea turtles in the ocean are ingestion of marine debris and collision 

with vessels. On land, by far the greatest adverse effect is loss of safe nesting sites. The cumulative 

effect of all human activity in the Gulf of Mexico on sea turtles is clearly negative (BOEM 2011a). 

Although the problem of marine debris has been recognized, it is far from being solved. Likewise, vessel 

collisions continue to injure and kill sea turtles. Both marine debris and vessel traffic (commercial and 

recreational) are expected to increase. Some progress has been made in protecting nest sites on 

beaches, but mortality is still high. Even when beaches are legally protected, domestic and feral 

predators take a toll on hatchlings. 

As human pressure on coastal habitats increases, natural habitats become less resilient and climactic 

events can pose disproportionate threats. Storms can destroy turtle nests and tear out important sea 

grass beds where young turtles spend their growing years. Increase pollutants from the land continue to 

degrade coastal habitats essential to young turtles. The proposed action would not contribute significantly 

to cumulative impacts on sea turtles. 
4.13.3.5 Cumulative Impacts to Coastal and Marine Birds

The human migration to coastal counties is expected to continue, causing fragmentation and destruction 

of sensitive coastal habitat. Critical wintering habitat for the piping plover on Gulf Coast beaches is under 

continuous pressure from incompatible recreational uses, including off-road vehicles. Residential, 

commercial, and recreational developments adversely affect coastal and marine birds through habitat 

degradation, direct physical disturbance, and increased predation pressure by domestic and commensal 

animals. Birds are at risk from strikes with aircraft and collisions with vehicles and from chemical 

releases in coastal areas. Sea level rise threatens coastal nesting, foraging, and roosting habitat for the 

piping plover and other shorebirds. The combined impact of rising sea level and increasing storm 

intensity threatens to flood up to 85 percent of piping plover habitat (Seavey and others 2011). 

The cumulative effect on shorebirds, such as the piping plover, from strikes with aircraft is expected to 

rise proportionally to increases in the number of private and commercial aircraft operating along the 

coast. Recreational pressure on beaches, foot traffic, off-road vehicles, and noise disturbance will 

continue to adversely affect nesting, roosting, and foraging piping plovers and their critical habitat, wood 

storks, and roseate terns, leading to nest destruction, breeding and chick rearing disturbances, and 

displacement of foraging areas. If disturbances exceed an unknown threshold of frequency, permanent 

displacement from preferred habitat or decreased reproductive success could occur. The proposed action 

would not contribute significantly to cumulative impacts on coastal or marine birds. 

4.13.3.6 Cumulative Impacts to Marine Mammals

The cumulative effects of all human activity in the Gulf of Mexico on marine mammals are adverse. 

Vessel strikes are a constant threat, even with the enormous efforts expended by the USCG, NOAA, and 

advocacy groups to educate operators. Human impacts on marine mammals in the Gulf of Mexico 

include fisheries interactions (such as gear entanglement, shootings by fishermen, or bycatch [accidental 

or indirect catch]), ship strikes, noise and chemical pollution, and general habitat deterioration or 

destruction. Direct hunting is of great concern worldwide, but does not occur in the Gulf of Mexico. 

However, indirect captures of animals in fishing nets and gear (bycatch) may account for the deaths of 

more marine mammals than any other cause (Northridge 2008; Read 2008; Hamer and others 2010). 

Ship strikes are a growing issue for most marine mammals and may reduce the population of a species, 

particularly in small populations (Laist and others 2001). As international shipping increases and ships 

become faster and larger, whale strikes will undoubtedly continue to pose a significant threat.

Noise is of particular concern to marine mammals because it can cause behavioral disturbance, injury, 

and in some cases, may lead to death (Würsig and Richardson 2008; Tyack 2009). Human-caused noises 

in the marine environment come from shipping, seismic and geologic exploration, sonar, and other types 

of pulses produced by government, commercial, and private sources. 

Chemical pollution is also of great concern, although for the most part, its effects on marine mammals 

are just starting to be understood (Reijnders and others 2008). Recently, the 5.5-year expedition of the 

Odyssey collected 955 biopsy samples from sperm whales around the world to provide a consistent 

baseline database of ocean contamination that can be used to measure future effects (Ocean Alliance 

2010). Chemical pollutants and pesticides flow into the marine environment from human use on land and 

are absorbed into the bodies of marine mammals, accumulating in their blubber or transferring to the 

young via mothers‘ milk (Fair and others 2010). 

Oil and other chemical spills are a specific type of ocean contamination known to have damaging effects 

on some marine mammal species (see Matkin and others 2008), as described in Section 4.8.1.4 and 

4.8.3.3. Potential behavioral responses are displacement from primary habitat and the disruption of 

social structure, changes in prey availability and in feeding activities and success, effects on reproductive 

behavior, and changes to migration. The proposed action would not contribute significantly to cumulative 

impacts on any species or stock of marine mammals. 
4.13.4 Cumulative Impacts to Coastal Species 

4.13.4.1 Diamondback Terrapin

The diamondback terrapin is threatened on land by some of the same human activities that threaten 

other coastal species, namely habitat destruction, road construction, and pollution. In addition, the 

terrapin faces dangers in the marine habitat, especially drowning in crab traps (Texas Parks and Wildlife 

Department 2011). Their coastal nesting areas have been degraded by beach erosion resulting from 

hurricanes and tropical storms. The diamondback terrapin is particularly vulnerable to habitat destruction 

because it returns to the same nest site year after year, has a low reproductive rate, limited survivorship, 

and a restricted home range (BOEM 2011a). The regulations outlined in NTL 2007-G04 (―Vessel-Strike 

Avoidance‖) and NTL 2007-G03 (―Marine Trash and Debris‖) serve to protect the diamondback terrapin 

from OCS-related activity while it is in the water. However, neither Shell nor BOEM can reduce the major 

onshore threats to this species, which are the result of general coastal development. The proposed action 

would not contribute significantly to cumulative impacts on the diamondback terrapin because the project 

would occur in the OCS far from the coastal waters that support the terrapin. 

4.13.4.2 Beach Mouse

The principal threat to all of the subspecies of beach mouse is habitat loss and fragmentation caused by 

development of beachfront property. A secondary effect of converting dunes to residential developments 

is the introduction of the house cat and the house mouse (Mus musculus). House cats readily prey on 

beach mice, and the house mouse competes with the native mice for food and burrow space. As natural 

populations of the beach mice become smaller and more isolated from one another, they becomes less 

able to recover from extreme events, such as hurricanes and floods (FWS 2009d). The proposed action 

would not contribute significantly to cumulative impacts on any subspecies of beach mouse because the 

project area is so far away from the coastal habitats that support these animals. 

4.13.5 Cumulative Impacts to Coastal and Marine Habitats

Most coastal and marine habitats worldwide are under increasing pressure from human development and 

expansion (Butchart and others 2010). Major stressors on most marine habitats are pollution, fishing 

practices, and global climate change (Pandolfi and others 2003; Lotze and others 2006). Global climate 

change can alter sea level, ocean temperature, circulation patterns, precipitation patterns, air and ocean 

chemistry, and abundance and distribution of species (NOAA 2010). The effects of these and other 

stressors may lead to the decline in the quality and distribution of marine habitats. 

The rise in sea level could flood some habitats including salt marshes, which may have limited capacity to 

expand landward because of coastal development (Hoegh-Guldberg and Bruno 2010; Nicholls and 

Cazenave 2010). Human activities from coastal development that act on intertidal, salt marsh (Taylor 

2008), estuarine, and seagrass (Short and Wyllie-Echeverria 1996) habitats include depositing fill material 

for development projects, disposing of dredge spoils, constructing aquaculture or salt ponds, and 

discharging waste products. Other stressors on salt marshes include encroaching invasive species and 

subsidence (Barras and others 2003; Taylor 2008). The introduction of nonnative species can 

dramatically affect the community interactions within habitats. Of equal concern is the widespread 

diversion of the water and sediments that sustain mudflats throughout the coastal zone (EPA 2007). 

Seagrass is also negatively affected by damage from boat propellers, increased sedimentation (particles 

settling on the seagrass) from dredging, and cloudy water from coastal development (Spalding and 

others 2003; Gulf of Mexico Program 2004). Threats to sandy intertidal shores include vehicle traffic 

(Lucrezi and others 2010), hurricanes, subsidence, and other erosive forces (for example, in Louisiana‘s 

barrier islands) (Barras and others 2003).

Coral reefs are under a variety of threats including coastal development (Field and others 2008), impacts 

from inland pollution and erosion, disease, exploitative and destructive fishing practices, global climate 

change, and oil extraction (Hickerson and others 2008). Early life stages of coral are particularly sensitive 

to oil exposure (Shafir and others 2007). Once a species is made vulnerable by these human-caused 
effects, impacts from natural events such as storms can be magnified (Friedlander and others 2008, 

2009). Deepwater corals and hardbottom communities are threatened by heavy bottom trawls (Lumsden 

and others 2007; NOAA and U.S. Department of Commerce 2010). As noted in the Multisale EIS, the 

incremental contribution of the proposed action to the cumulative impacts on regional resources is not 

significant (MMS 2007b).

4.13.6 Cumulative Impacts to Archaeological Resources

Cumulative impacts to historic archaeological resources are generated by activities that disturb the 

seafloor, including exploration and development, dredging, anchoring, sand mining, deployment of 

artificial reefs, liquefied natural gas or other alternative energy development, and bottom trawling. 

Despite regulations enforced by BOEM that require pre-project surveys for archaeological resources, 

some impacts likely occur because not every shipwreck or archaeological site is detected using current 

survey techniques (BOEM 2011a). The limited spatial scale of the proposed action would not contribute 

to the cumulative impacts on archaeological resources because Shell has performed the required surveys 

to document the absence of shipwrecks in the lease area. 

4.13.7 Cumulative Impacts to Socioeconomic Resources

Cumulative impacts to socioeconomic conditions such as the commercial and recreational fishing 

industries, non-fishing recreation and tourism, coastal employment, public health and safety, land use, 

and other marine uses are complex and difficult to quantify because they are mediated by numerous 

individuals making independent decisions. Variables such as the strength of the national and local 

economies, the price of energy, fluctuations in the domestic job market, and the occurrence of natural 

disasters influence socioeconomic conditions in the Gulf states. Most purposeful human activities in the 

Gulf of Mexico have a strong positive effect on socioeconomic conditions, but also pose some 

environmental risk that can have indirect adverse effects. The proposed action would contribute to either 

a positive or synergistic effect on socioeconomic conditions in the region. 

5.0 Environmental Hazards

5.1 Geologic Hazards

The shallow hazards report states that the wellsites are free of any major geological hazards and are 

suitable for the proposed activities (C&C Technologies 2009). Initial EP Section 6a provides geological 

and geophysical data to support this conclusion.

5.2 Severe Weather

Severe weather short of a hurricane is not expected to pose any risk to the drillship or to interfere with 

the proposed action. The drillship and associated equipment were designed to operate for months at a 

time in offshore locations exposed to high winds, strong currents, and oceanic waves. If severe weather 

threatens to interfere with safe operation of support vessels and helicopters, activities would be halted 

until conditions improved. Shell would follow the procedures detailed in its Hurricane Evacuation Plan if 

conditions warranted.

5.3 Currents and Waves

Wind speed and direction, sea states, and currents would be monitored throughout the drilling period. 

Drillships and associated equipment are designed to function under both typical and extreme 

oceanographic conditions of the Gulf of Mexico, including storm-generated waves, high winds, and 

subsea disturbances related to the loop current. Extreme weather such as hurricanes can disrupt drilling 

by making it unsafe for support vessels and helicopters to operate but is not considered a threat to the 

drillship or the well.
6.0 Mitigation Measures

Mitigation measures that comply with laws, regulations, lease stipulations, and NTLs are considered an 

integral part of the proposed action. The project was designed to ensure compliance with all applicable 

and permitted pollution controls, including air emissions, discharges to water, and disposal of solid 

wastes. Shell‘s OSRP provides a framework for the overall project, including the activities in the Initial 

EP Section 2j. Shell has obtained International Organization for Standardization (ISO) 14001 

certification and continuously promotes pollution reduction. Shell is committed to adopting the mitigation 

measures shown in Table 12 in addition to those required by 30 CFR 250:
Table 12. Mitigation and Conservation Measures for Marine Species and Habitats

Type of Mitigation

Purpose of Mitigation Measure

Reduce Collision / 

Physical Harassment 

with Marine Mammals 

and Sea Turtles 

Reduce 

Probability and 

Impact of 

Accidental Spill

Reduce Impacts 

to Fisheries, EFH, 

and Sensitive 

Habitats

Reduce Routine 

Pollution, 

including 

Marine Debris

Protect 

Cultural 

Resources 

Conduct pre-tour and pre-job safety meetings; 

daily reminders to all staff to maintain safety 

and minimize pollution at all times; discuss 

environmental consequences.

√ √ √ √ √

Inspect and clean pollution pans on all tools 

arriving on the drillship; check plugs before 

tools leave the dock or are placed on a vessel.

√ √ √

Inspect pollution pans and hydraulic lines and 

reservoirs on the drillship.

√ √ √

Check direct overboard drains on the drillship 

regularly to verify plugs are installed. 

√ √ √

Place containment dikes around oil and drum 

storage areas, fuel vents, and fuel storage 

tanks.

√ √ √

Transport used oil and fuel to recycling 

facilities on shore.

√ √ √

Check direct overboard drains on the rig 

regularly to verify drain plugs are installed. 

√ √ √

Collect and secure solid waste daily; transport 

waste to shore for disposal or recycling by 

vetted vendor.

√ √

Inspect and change fuel hoses and SBM as 

appropriate. 

√ √ √

Use spill prevention fittings on liquid take-on 

hoses as appropriate.

√ √ √

Dispose of unused paint by drying in the 

container and shipping to shore as waste. 

√ √ √

Use Envirorite hydraulic fluid on board. √ √
Type of Mitigation

Purpose of Mitigation Measure

Reduce Collision / 

Physical Harassment 

with Marine Mammals 

and Sea Turtles 

Reduce 

Probability and 

Impact of 

Accidental Spill

Reduce Impacts 

to Fisheries, EFH, 

and Sensitive 

Habitats

Reduce Routine 

Pollution, 

including 

Marine Debris

Protect 

Cultural 

Resources 

Use low sulfur fuel. √

Provide marine debris awareness and 

elimination training and information on 

initial employment and in an annual 

refresher. Verify training during rig 

orientation for new arrivals. (NTL 2007-

G03).

√ √ √

Provide marine mammal observers during 

seismic operations. If warranted, provide 

observers during drilling operations NTL 

2007-G04).

√

Support vessel operators reduce vessel speed 

when marine mammals or sea turtles are in 

the vicinity (NTL 2007-G04).

√

Maintain spatial buffer around sensitive 

benthic communities (NTL 2009-G40).

√

Require pilots to maintain recommended 

altitudes over sensitive habitats and species.

√

Use drillship that complies with cooling 

water intake provisions of GMG 290000.

√

Comply with NPDES permitted effluent 

limits; complete daily NPDES reports.

√ √

Maintain spatial buffer around archaeological 

resources (NTL 2005-G07).

√
7.0 Consultation

No agency consultation on potential impacts of the proposed project was warranted.

8.0 Preparers

Tetra Tech, Inc. prepared this EIA under the direction of Shell. The following people contributed 

technical expertise to this document:

 Lori Downs (Environmental Team Leader, Shell Exploration & Production Co.);

 Rob Kuehn (Environmental Engineer, Shell Exploration & Production Co.);

 Jeff McMenis (Environmental Engineer, Shell Exploration & Production Co.);

 Tracy Albert (Regulatory Specialist, Offshore Technical Compliance LLC);

 Sylvia Bellone (Regulatory Specialist, Shell Exploration & Production Co.);

 Randy Allen (Plans Specialist, Shell Exploration & Production Co.)

 Alec Bray (Team Leader—Mesozoic, Shell Exploration & Production Co.);

 Christy Gibson (Staff Geologist, Shell Exploration & Production Co.);

 Hongbo Lu (Senior Geologist, Shell Exploration & Production Co.);

 Roger Van Noort (Senior Well Engineer, West Boreas and South Deimos Wells, Shell 

Exploration & Production Co.);

 June Mire, Ph.D. (NEPA Specialist and Project Manager, Tetra Tech);

 Stephen Compton (Senior Project Manager, Tetra Tech); 

 Kim Gorman (NEPA Specialist, Tetra Tech); and

 Jennifer Laslovich (GIS/Remote Sensing Specialist, Tetra Tech).
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Appendix A

Matrix of Impact-Producing Factors 

and Environmental Resources 
Environmental Resources

Potential Impact-producing Factors

Drilling Rig 

Presence 

(incl. noise 

& lights)

Physical 

Disturbance 

to Seafloor

Air Pollutant 

Emissions

Effluent 

Discharges

Water 

Intake

Onshore 

Waste 

Disposal

Marine 

Debris

Support 

Vessels

Accidents

Small Fuel 

Spill

Large Oil 

Spill 

Physical/Chemical Environment

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

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

Seafloor Habitats and Biota

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

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

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

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

Eastern Gulf live bottoms -- --(3) -- --(3) -- -- -- -- -- --

Threatened, Endangered, and Protected Species and Critical Habitat

Sperm whale (endangered) X(8) -- -- -- -- -- -- X(8) X(6,8) X(6,8)

Florida manatee (endangered) -- -- -- -- -- -- -- X(8) -- X(6,8)

Endangered mysticete whales -- -- -- -- -- -- -- -- -- --

Non-endangered marine mammals (protected) X -- -- -- -- -- -- X X(6) X(6)

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

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

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

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

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

Coastal and Marine Birds

Marine and pelagic birds X -- -- -- -- -- -- X X(6) X(6)

Shorebirds and coastal nesting birds -- -- -- -- -- -- -- X -- X(6)

Fisheries Resources

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

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

Archaeological Resources

Shipwreck sites -- --(7) -- -- -- -- -- -- -- X(6)

Prehistoric archaeological sites -- --(7) -- -- -- -- -- -- -- X(6)

Coastal Habitats and Protected Areas

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

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

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

Socioeconomic and Other Resources

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

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

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

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

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

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

X = potential impact

-- = negligible or no impact

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

anchors will be on the seafloor within the following:

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

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

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

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

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

Topographic Features Stipulation attached to an OCS lease.

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

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

(2) Activities with any bottom disturbance within an OCS lease block protected 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 BOEM as being in water depths 300 m or greater.

 The proposed action will not impact high-density deepwater benthic communities. No high-density 

chemosynthetic communities or coral communities occur within 1,500 ft (457 m) of any drilling 

mud/cuttings discharge location. 

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

 H2S has not been characterized in MC 525; concentrations of H2S are unknown.

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you 

determine would impact these environmental resources. If the proposed action is located a sufficient distance 

from a resource that no impact would occur, the EIA can note that in a sentence or two.

 Impacts of accidental fuel or chemical spills could adversely affect these resources. Impacts are analyzed 

in Section 4.0.

(7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by 

BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, 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 known archaeological resources occur within the project area. 

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

sea turtles or their critical habitats. 

 Potential adverse effects on threatened and endangered species are analyzed in Section 4.0 within the 

section on each taxonomic group.

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

 Not applicable.
SECTION 19: ADMINISTRATIVE INFORMATION

A. Exempted Information Description (Public Information Copies Only)

The following attachments were excluded from the public information copies of this plan:

Section 1b. OCS Plan Information form – Bottom hole locations & proposed total depth

Section 2j. Blowout Scenario – confidential information for NTL 2010-N06 calculation

Section 3a. Geologic Description

Section 3b. Structure Contour Maps

Section 3c. Interpreted 2D or 3D seismic line(s)

Section 3d. Cross Section(s)

Section 3e. Shallow Hazards Report

Section 3f. Shallow Hazards Assessment – confidential data

Section 3g. High-Resolution Seismic Lines & Top Hole Progs

Section 3h. & 3i. Stratigraphic Column with Time vs. depth table

B. Bibliography

AUV Hazard study prepared by C&C Technologies, February 2009, Project #083926-084483, for Mississippi 

Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, and 613, for Mississippi Canyon 525, 

Proposed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400-2040 for DeSoto Canyon Blocks 485 and 529 and Mississippi 

Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and Murphy E&P‘s 

previously submitted shallow hazards report No. 2400-2070, prepared by Fugro Geoservices, for OCS-G 19960, 

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

Environmental Impact Analysis prepared by Tetra Tech, Inc., September 2011

Shell Offshore Inc. Regional Oil Spill Contingency Plan, August 2011