UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)
Plans Section, Office of Field Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - S-07480

Type - Supplemental Exploration Plan

Lease(s) - OCS-G22919 Block - 984 Mississippi Canyon Area OCS-G22920 Block - 985 Mississippi Canyon Area OCS-G31534 Block - 940 Mississippi Canyon Area

Operator - Shell Offshore Inc.

SubseaWells I, G, F, E, D, J, K, H(ST01)and No.1STwest

DP SEMISUBMERSIBLE

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

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

Michelle Griffitt
Plan Coordinator Description -

Rig Type - Subject: From: August 30, 2011

### 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
T elex http://www.shell.com/eandp-en Email sylvia.bellone@shell.com

May 9, 2011

Ms. Liz Peuler, Section Chief Bureau of Ocean Energy Management, Regulation and Enforcement
1201 Elmwood Park Boulevard New Orleans, LA 70123-2394

Attn: Plans Group MS 5231

SUBJECT: Supplemental Exploration Plan – Mississippi Canyon Block 940, 984 and 985 OCS-G 31534, OCS-G 22919 and OCS-G 22920

Gentlemen:

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 yo ur approval of this Supplemental Exploration Plan requesting approval to drill Well Locations I, J an d K to the previously approved subject leases.

The NTL 2010-06 Worst Case Blowout requirements fo r our Regional Oil Spill Response Plan highest exploration well was previously submitted October 26 , 2010 with our Supplemental Exploration Plan for Mississippi Canyon Blocks 391, 392 and 348, Plan Control No. R-5066.

This Plan consists of a series of attachments desc ribing our intended operat ions. 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 for this Plan is attached to the confidential copy.

Should you require additional information, please contact me as indicated above.

Sincerely,

Sylvia A. Bellone

## SHELL OFFSHORE INC.

SUPPLEMENTAL EXPLORATION PLAN

for

MISSISSIPPI CANYON BL OCK 940 (OCS-G 31534)
MISSISSIPPI CANYON BL OCK 984 (OCS-G 22919) MISSISSIPPI CANYON BLOCK 985 (OCS-G 22920)



# PUBLIC INFORMATION

PREPARED BY:



## Sylvia A. Bellone Regulatory Specialist

504.728.7215

Sylvia.bellone@shell.com

### REVISIONS TABLE Plan S-7480:

Date of Request Plan Section What Changed Date Replied

5/25/11 Plan Section 1A

Section 3F Added sentence about TA & installing corrosion cap after work is complete. Revised for previously approved wells and
included an ESR. 6/13/11

7/13/11 Section 7A & 7b Updated waste and discharge table 7/13/11

7/14/11 Sections 3F & 6A Updated wells
discussed in
assessments 7/14/11

Section 9 Updated worse case discharge comparison table for new regional oil spill response WCD number 8/9/11SUPPLEMENTAL EXPLORATION PLAN MISSISSIPPI Canyon Area Blocks 940, 984 & 985

Table of Contents

1. Plan Contents
2. General Information
3. Geological and Geophysical
4. Hydrogen Sulfide - H 2 S
5. Mineral Resource Conservation
6. Biological, Physical and Socioeconomic Information
7. Waste and Discharge Information
8. Air Emission Information
9. Oil Spill Information
10. Environmental Monitoring
11. Lease Stipulations
12. Environmental Mitigation Measures
13. Related Facilities and Operations Information
14. Support Vessels and Aircraft
15. Onshore Support Facilities Information
16. Sulphur Operations
17. Coastal Zone Management Act Information
18. Environmental Impact Analysis
19. Administrative InformationSECTION 1: PLAN CONTENTS

A. DESCRIPTION, OBJECTIVES & SCHEDULE

This Supplemental Exploration Plan (EP/Plan) with a ppendices, including an Environmental Impact Analysis (EIA) found in Section 18, describes the drilling activiti es Shell Offshore Inc. (Shell) plans to conduct with respect to OCS-G 31534, 22919 & 22920, Mississippi Cany on Blocks 940, 984 and 985. Wells A and B were submitted in Plan N-6091 by Energen Resources MAQ, Inc. in April 1988. Well C was submitted in Plan S-4798 by Energen Resources MAQ, Inc. in November 1998. Wells D through G were submitted under Plan N-9220 and are not drilled. Well H (Well #1 and 3 sidetracks) was drilled by Anadarko under Plan N-9393 and also covered in Plan R-5022 approved 3/17/2010. This Plan will be fo r the drilling of three new Wells I, J and K. The wells will be drilled and temporarily abandoned (cement plug and corrosion cap) until the wells are completed and developed under future plan. If the well is unsuccessful, it will be permanently plugged and abandon in accordance with BOEM regulations.

Shell’s Plan, as detailed in its EP, is to use a single se mi-submersible, the M/V Noble Danny Adkins or equivalent (the “Rig”), to drill up to three (3) exploration wells in the Mississippi Canyon Area, located approximately 67 miles from the nearest coastline (Louisiana), 117 miles fro m the supply base at Port Fourchon, Louisiana, and 92 miles from the helicopter terminal at Amelia, Louisiana. Water depths in the leas e range from approximately 3,978’ to 4,164’. The initial drilling activities are pl anned to commence on or about October 2011 and take approximately 145 days per well. The ti meframe to complete the initial drilli ng activities is an estimate based on the best available information regarding downhole cond itions likely to be encountered while drilling each well
and not intended to be a limitation. The timeframe for dr illing the first well will further define the timing for further development of the prospect.

The Rig is a DP Semi-submersible and is equipped with stat e-of-the-art drilling and well control equipment. The Rig will comply with the requirements in the Interim Final Rules. The drilling activities will be supported by the support vessels and aircraft as well as onshore support facili ties as listed in Sections 14 and 15 of the EP. Shell has employed or contracted with trained personnel to ca rry 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 940 drilling program. Shell believes that the best way to manage blowouts is to prevent them from happening. Significant effort goes into the design and execution of wells and into building and maintaining staff competence. In the unlikely event of a spill, Shell’s Regional OSRP (October 2010) 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 br idging, 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 w ill have trained personnel and monitoring programs in place to ensure such compliance.

B. LOCATION

See attached BOEM forms and location plat.C. RIG SAFETY AND POLLUTION FEATURES :

The rig (Noble Danny Adkins 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 infl ow detection and well control, monitoring for loss of circulation and seepage loss, and casi ng design will be our primary safety measures. Primary pollution prevention measures are contaminated and non-cont aminated drain system an d oily water processing.

DRAIN SYSTEM POLLUTION FEATURES

Drains are provided on the Rig in all spaces and on al l decks where water or oil can accumulate. The drains are divided into two categories, non-contaminated an d contaminated. All deck drains are fitted with a removable strainer plate to prevent debris entering the system.

Deck Drainage from rainfall, Rig washing, deck washin g, 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 unlike ly that hydrocarbons will be found.

Drains within 50 feet of a designated chemical stor age 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 designat ed 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-plat es 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) Mud Drain System

None4) Oily Water Processing

Oily water is collected in an oily water tank. It mu st be separated and not pumped overboard until oil
content is < 15 ppm. The separated oil is pumped to a dirt y oil tank and has to be sent ashore for disposal. On board the 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 sh een test then the water/oil mixture is pumped to a dirty oil tank and sent to shor e 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 applicab le NPDES permits. See Attachment 18, EIA, Section C.1.1.2, Water Quality.

5) Lower Hull Bilge System

• The main bilge system is designed to drain the pontoons. There are Goulds electrically driven, self priming centrifugal pumps - one for each main pump room. The aux pumps can be pump out with the bilge pump but has to be line 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 Br idge, and have audible and visual bilge alarms set for high and low levels. • Portable submersible pumps are carried onboard th e 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. Th ey 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.

6) 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.

7) 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 environment al safety. All three anchor winch windlasses have skimmer tanks and are subjected to sheen tests before discharge as well.

8) 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-hazard ous drains from nonhazardous areas. • To prevent migration of hazardous materials an d flammable gas from hazardous to non-hazardous areas, the drainage systems are segregated. • The Rig drainage systems tie into oily water separa tors 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. 9) Rig Floor DrainageThe Rig floor has been outfitted with a Facet In ternational MAS 34-3 separator. The separator has coalescent plates that remove the solids from th e drainage, and the remain ing 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 2 separators and cleaned furt her to reduce oil content to less than 15 ppm.

10) Columns #3 & 4

The drains on the decks and machinery spaces are sepa rated at mid ship and directed to either the #3 or #4 columns. The separators in these columns go th rough three cycles of circulation and remove oil to less than 15ppm, then discharge the clean product to sea.

11) Main Engine Rooms

• The engine rooms have their own drainage and ha ndling 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 dirt y oil tank and the clean water (less than 15ppm) 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

12) Helideck Drains

The heli-deck 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:

3⁄4 The overboard piping valves and hydrocarbons ta ke on valves are closed and locked. To unlock overboard or take on valves a permit has to be filled out. 3⁄4 The oily water collection tank overflow valve is closed. 3⁄4 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. 3⁄4 The BOP test area drains are norm ally lined-up to drain overboard. 3⁄4 The oily water separator continuously circulates the oily water collection tank. Waste oil is discharged into the waste oil tank and oily wa ter is re-circulated back into the oily water collection tank. Clean water is pumped overboar d, which is controlled/monitored by the oil content detector, set at 15 ppm. 3⁄4 The solids control system is capable of being isolated for cuttings collection. 3⁄4 The bilge system is normally pumped directly over board after a sheen test has been performed. 3⁄4 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 au dible alarm on the ballast control panel.D. Storage Tanks - Noble Danny Adkins

Type of Storage Tank Type of Tank Number of Total Fluid Facility Capacity (bbls) Tanks Capacity (bbls) Gravity (API)

Fuel oil MODU 2652 1 2652 No. 2 diesel Fuel oil MODU 1,743 1 1743 No. 2 diesel
Fuel oil MODU 5767 1 5767 No. 2 diesel
Fuel oil MODU 4399 1 4399 No. 2 diesel
Fuel oil MODU 2652 1 2652 No. 2 diesel
Fuel oil MODU 3250 1 3250 No. 2 diesel
Fuel oil MODU 4399 1 4399 No. 2 diesel
Fuel oil MODU 2618 1 2618 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 No. 2008-G04 the proposed operations co vered by this EP do not require Shell to specifically address the discharges of oils and gr eases from the Rig during rainfall or routine operations. Nevertheless, Shell has provided this information as part of its response to 1(c) above.

F. Additional Measures

3⁄4 HSE (health safety and environment) are the pr imary 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.

3⁄4 All tools that come to and from the Rig have their pollution pans inspected, cleaned and confirmation of plugs installed prior to leaving dock and prior to loading on the boat.

3⁄4 Preventive Maintenance of Rig equipment includes vi sual inspection of hydrau lic lines and reservoirs
on routine scheduled basis.

3⁄4 All pollution pans on Rig are inspected daily.

3⁄4 Containment dikes are installed around all oil contai nment, drum storage areas, fuel vents, and fuel storage tanks.

3⁄4 All used oil and fuel is collected and sent in for recycling.

3⁄4 Every drain on the Rig is assigned a number on a ch ecklist. The checklist is used daily to verify drain plugs are installed.

3⁄4 All trash containers are checked and emptied daily. The trash containers are kept covered. Trash is disposed of in a compac tor and shipped in via boat.

3⁄4 The Rig is involved in a recycling program for ca rdboard, plastic, paper, glass, and aluminum.

3⁄4 Fuel hoses and SBM are changed on annual basis.

3⁄4 TODO spill prevention fittings are installed on all liquid take on hoses.

3⁄4 Waste paint thinner is recycled on board with a solvent still to reduce hazard of shipping and storage.

3⁄4 All equipment on board utilizes Envirorite hydrauli c fluid as opposed to hydraulic oil. Shell has
obtained ISO14001 certification.U. S. Department of the Interior OMB Control Number: 1010-0049 

### Minerals Management Service OMB Approval Expires: August 31, 2006 OCS PLAN INFORMATION FORM


### General Information
Type of OCS Plan: X Exploration Pl an (EP) Development Operations Coordination Document (DOCD) Company Name: Shell Offshore Inc MMS Operator Number: 0689

Address: P. O. Box 61933 Contact Person: Sylvia Bellone

New Orleans, LA 70161-1933 Phone Number: (504) 728-7215

E-Mail Address: sylvia.bellone@shell.com

Lease(s): OCS-G 22920 & 22919 Area: Miss. Canyon Block( s): 984, 985 Project Name (If Applicable): NA

Objective(s): X Oil Gas Sulphur Salt Onshore
Base:Fouchon &
Boothville Distance to Closest Land (Miles): 67



### 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 a nd/or manifolds Commence production

Installation of lease term pipelines Other (Specify and describe)

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

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

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

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

Have all of the surface locations of your proposed ac tivities been previously reviewed and approved by
MMS? Locs D, E, F & G apprvd Plan Ctl No. N-9220 7/30/08, Loc H apprvd Plan Ctr No. N-9383 6/12/09 *X Yes X No



### Tentative Schedule of Proposed Activities
Proposed Activity Start
D t End
D t No. of Days

See attached



### Description of Drilling Rig Description of Production Platform
Jackup Drillship Caisson Tension leg platform
Gorilla Jackup Platform rig Well protector Compliant tower

Semisubmersible Submersible Fixed platform Guyed tower

X DP Semisubmersible Other (Attach Description) Subsea
manifold Floating production system Drilling Rig Name (If Known): Noble Danny Adkins or similar rig 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 (August 2003) Page 1 of 11 PUBLIC INFORMATION

### Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Drill Well I & ST 10/01/2011 04/28/2011 210

Drill Well G 9/30/2012 2/22/2013 145

Drill Well F 9/30/2013 2/22/2014 145

Drill Well E 9/30/2014 2/22/2015 145

Drill Well D 9/30/2015 2/22/2016 145

Drill Well J 9/29/2016 2/21/2017 145

Drill Well K 9/29/2017 2/21/2018 145 Sidetrack Well 1 (H surface location drilled) 9/29/2018 12/3/2018 65

MMS Form MMS-137 (August 2003) Page 2 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well D Subsea Completion

Anchor Radius (if applicable ) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22919

Area Name Mississippi Canyon

Block No. 984

Blockline Departures (in feet) N/S Departure: 7255 FNL

E/W Departure: 5075 FEL

Lambert X-Y coordinates X: 945,325

Y: 10,162,025

Latitude/ Longitude Latitude 27.98637884

Longitude -89.15419168

TVD (Feet): MD (Feet): Water Depth (Feet): 4,097



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 3 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well E Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22920

Area Name Mississippi Canyon

Block No. 985

Blockline Departures (in feet) N/S Departure: 1260 FNL

E/W Departure: 6259 FEL

Lambert X-Y coordinates X: 959,981

Y: 10,168,020

Latitude/ Longitude Latitude 28.00356754

Longitude -89.10911696

TVD (Feet): MD (Feet): Water Depth (Feet): 4,196



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 4 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well F Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22920

Area Name Mississippi Canyon

Block No. 985

Blockline Departures (in feet) N/S Departure: 2906 FNL

E/W Departure: 7244 FEL

Lambert X-Y coordinates X: 958996

Y: 10166374

Latitude/ Longitude Latitude 27.99899457

Longitude -89.11208014

TVD (Feet): MD (Feet): Water Depth (Feet): 4170



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 5 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well G Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22919

Area Name Mississippi Canyon

Block No. 984

Blockline Departures (in feet) N/S Departure: 807.50 FNL

E/W Departure: 6977.25 FWL

Lambert X-Y coordinates X: 941537.24

Y: 10168472.51

Latitude/ Longitude Latitude 28.0039244

Longitude -89.1662783

TVD (Feet): MD (Feet): Water Depth (Feet): 4015



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 6 of 11 PUBLIC INFORMATION

### 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): We ll 1ST (H) S ubsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22919

Area Name Mississippi Canyon

Block No. 984

Blockline Departures (in feet) N/S Departure: 807.50 FNL

E/W Departure: 7077.25 FWL

Lambert X-Y coordinates X: 941637.24

Y: 10168472.51

Latitude/ Longitude Latitude 28.0039278

Longitude -89.1659685

TVD (Feet): MD (Feet): Water Depth (Feet): 4044



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 7 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well I Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31534

Area Name Mississippi Canyon

Block No. 940

Blockline Departures (in feet) N/S Departure: 730 FSL

E/W Departure: 8209 FWL

Lambert X-Y coordinates X: 942769

Y: 10170010

Latitude/ Longitude Latitude 28.0082106

Longitude -89.1625469

TVD (Feet): MD (Feet): Water Depth (Feet): 3978



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 8 of 11 PUBLIC INFORMATION

### 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, re ference previous name): Well I-ST (West) S ubsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31534

Area Name Mississippi Canyon

Block No. 940

Blockline Departures (in feet) N/S Departure: 730 FSL

E/W Departure: 8209 FWL

Lambert X-Y coordinates X: 942769

Y: 10170010

Latitude/ Longitude Latitude 28.0082106

Longitude -89.1625469

TVD (Feet): MD (Feet): Water Depth (Feet): 3978



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 9 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well J Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 31534

Area Name Mississippi Canyon

Block No. 940

Blockline Departures (in feet) N/S Departure: 502 FSL

E/W Departure: 8366 FWL

Lambert X-Y coordinates X: 942926

Y: 10169782

Latitude/ Longitude Latitude 28.0075914

Longitude -89.1620480

TVD (Feet): MD (Feet): Water Depth (Feet): 3978



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MM S collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it disp lays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 10 of 11 PUBLIC INFORMATION

### 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 structur e, reference previous name ): Well K Subsea Completion

Anchor Radius (if applicab le) in feet: NA X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 22919

Area Name Mississippi Canyon

Block No. 984

Blockline Departures (in feet) N/S Departure: 476 FNL

E/W Departure: 6658 FWL

Lambert X-Y coordinates X: 941218

Y: 10168804

Latitude/ Longitude Latitude 28.0048189

Longitude -89.1672855

TVD (Feet): MD (Feet): Water Depth (Feet): 4025



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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this info rmation as part of an applicant’s Exploration Plan or Development Operations Coordination Document submi tted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We w ill protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not co nduct or sponsor, and a person is not required to respond to, a collection of information unless it displa ys a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The pu blic reporting burden for this form is included in the burden for preparing Exploration Plans and Development Op erations 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 (August 2003) Page 11 of 11 PUBLIC INFORMATIONSECTION 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 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 SEP are satisfied by an area-wide bond furnished and maintained according to 30 CFR Part 256, subpart I; NTL No. 2000-G16, Guideline for General Lease Surety Bonds;” and National NTL No. 2003-N06, “Supplemental Bond Procures.”

G. Oil Spill Financial Responsibility (OSFR)

Shell Offshore Inc (SOI), BOEMRE Operator Number 0689, has demonstrated oil spill financial responsibility for the facilities proposed in the EP according to 30 CFR Part 253, and NTL No. 99-N01, “Guidelines for Oil Spill Financial Responsibility for Covered Facilities.”

H. Deepwater well control statement

Shell Offshore Inc (SOI), BOEMRE 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 Incorpor ated (SOI) pursuant to the guidance provided in the Bureau of Ocean Energy Management, Regulation and Enforcement’s (BOEMRE) 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 design and exec ution of wells and into building and maintaining staff competence. Shell continues to invest independently in Research and Development (R&D) to improve the safety and reliability of our well systems. Shell intends to comply with all applicable laws, regulations, rules
and Notices to Lessees.

Shell is a founding member of the Marine Well Contai nment Corporation (MWCC) and will have access to an integrated subsea well control and containment system that can be rapidly deployed through the MWCC. The MWCC is a non-profit organization that owns, manage s, and provides fully trained crews and operates the subsea containment system during a response. The near term contai nment response capability will be
addressed in Shell’s NTL No. 2010-N10 submission at the time an Application to Drill (APD) is submitted and
will include lessons learned and from the Macondo response.

. Shell is investing in R&D to improve containment systems. Also, Shell is a member of Cl ean Caribbean America (CCA), Marine Spill Response Corporation (MSRC), Clean Gulf Associates (CGA), an d OSRL/EARL to provide the resources necessary to respond to a spill as outlined in our Regional Oil Spill Response Plan (OSRP, October 2010).

The Worst Case Discharge (WCD) blowout scenario for Vito is calculated for the MC 940 #1 ST3BP00 location, which is planned as a Northeast penetration of th e Lower Miocene NMP Sand, based on the guidelines outlined in NTL No. 2010-N06 along with subsequent Frequently Asked Questions (FAQ). The WCD for MC 940 #1 ST3BP00, or a similarly target ed well, falls below the WCD exploratory scenario for MC 391 C included in our Regional OSRP (October 2010). In the unlikely even t of a spill, Shell’s Regional OSRP (October 2010) 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 bri dging, obstructions in the we llbore, reservoir barriers, or early intervention.

Uncontrolled blowout (volume first day) 314,000 bbl Uncontrolled blowout rate (first 30-days average daily rate) 280,000 bopd Duration of flow (days) based on relief well 185 days Total volume of spill (bbls) for 185 days 48 MMBO

Table 1 Worst Case Discharge Summary

The Vito discovery is located approximately 67 miles from the nearest coastline in the Gulf of Mexico (GOM), in water depths of approximately 4100 feet (ft) across the discovery. Vito is a three-way, sub-salt closure against salt and salt weld and is located approximate ly 12 miles south of the Mars platform in Mississippi Canyon. The crest of the Vito NMP structure at the MC940 #1 ST3BP00 is at approximately 28,120’ TVDss (28,202’ TVD). To date, the Vito part nership has drilled four penetrations at Vito, the discovery well, MC984
#1 ST00 BP01 and 3 subsequent sidetracks; the MC984 #1 ST00 BP02, the MC940 #1 ST1 BP00, and the MC984 #1 ST2 BP00. All wells/sidetracks at Vito have been drilled from Surface Location H. The discovery well and the subsequent sidetracks were drilled in 2009 – 2010, with operations suspended in May 2010 due to the Drilling Moratorium. The primary objective of the proposed MC940 #1 ST3 BP00, with predicted WCD flow potential, is the NMP reservoir of Lower Miocene ag e. Additional WCD scenarios were evaluated for Vito,
in which other sands and well locations were consider ed. However, the WCD numbe rs for these wells/sands
are lower than the WCD number calculated for the NMP as these sands are thinner, of lower quality, and flowed at substantially lower rates than the NMP case re presented for the WCD. These shallower sands will be cased off prior to the well path pe netrating the NMP reservoir package.

1) PurposePursuant with 30 CFR 250.213(g), 250.219, 250.250, an d NTL No. 2010-N06, this document provides a blowout scenario description, further information re garding any potential oil spill, the assumptions and
calculations used to determine the WCD and the measur es taken to firstly enhance the ability to prevent a blowout and secondly to respond and manage a blowout sc enario if it were to occur. These calculations are
based on best technical estimates of subsurface parameters that are derived from the offset Vito wells and seismic. 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 inform ation 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 and the resultin g subsea well blowout and recovery operations of the exploration well at the MC-252 Macondo location.

3) Information Requirements

a) Blowout scenario

All well and sidetrack locations addressed in this EP were assessed for WCD using the expected wellpath, the expected reservoir thickness, structural elevation, and rock/fluid properties for each.
The MC940 #1 ST3 BP00 deviated well from the approved “H” surface location and a bottom hole location (BHL) on the northern crest of the Vito structure represented the well with the highest flow potential. The MC940 #1 ST3 BP00 well will be drilled through the NMP reservoir as outlined in the Geological and Geophysical Information Section of the Revised Vito EP, and described above, using a subsea wellhead system, conductor, surface and in termediate casing program, and using a DP rig with a marine riser and subsea blowout preventer (BOP). A hydrocarbon influx and a well control event are modeled to occur from the Lower Miocene NMP reservoir. Other sands were modeled; however, the NMP represented the highest WCD nu mber. The simulated blowout modeled results in unrestricted flow from the well at the seafloor, whic h 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

Table 2 Estimated Flow Rates of a Potential Blowout

c) Total volume and maximum duration of the potential blowout

Duration of flow (days) 185 days total duration to drill relief well (14 rig mob, 3 transit, 135 sp ud to top NMP, 33 ranging).
Total volume of spill (bbls) 48 MMBO based on 185 days flowing. Note: From CMG dynamic reservoir models

Table 3 Estimated Duration and Volume of a Potential Blowout Category EP Type of Activity Drilling Facility Location (area/block) MC 984 Facility Designation DP Distance to Nearest Shoreline (miles) 67 Statute miles Uncontrolled blowout (volume first day) 314,000 bbl Uncontrolled blowout rate (first 30-days average daily rate) 280,000 bopdThere is usually a decline in the discharge rate as time progresses, which is illustrated by the
differences between the first 24-hour volume and 30 -day average rate. At very short times, e.g. during the first 24 hours, the pressure profile in the reservoir changes from the moment when a well first starts flowing to a pseudo-s teady state pressure profile with time, and as a result the rate declines. At somewhat longer ti me scales, effects such as rese rvoir voidage and the impact of boundaries can cause the rate to drop continuously with production. Simulation and material balance
models can include these effects and form the ba sis of the NTL No. 2010-N06 estimates for 24-hour and 30-day rates as well as maximum duration volumes.

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

Omitted from Public Information Copies.

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 velo cities 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 ma y fail/collapse/bridge over within the span of a few days, significantly reducing the outflow rates. However, this WCD scenario does not include any bridging.

f) Likelihood for intervention to stop the blowout.

Safety of operations is our top priority. Maintainin g well control at all times to prevent a blowout is the key focus of our operations. This is derive d 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 componen ts with the intent to seal off the well bore. As a minimum, the Shell contracted rig fleet in the GOM will have redundancies meeting Interim Final Rule and the Drilling Safety Rule with respect to Remotely Operated Vehi cle (ROV) hot stab capabilities, a deadman system, and an autoshear system. The rig to be used on Vito will be the Noble Da nny Adkins, a dynamically positioned MODU. The BOP stack on this rig has two shearing rams for addi tional redundancy. Also, the Noble Danny Adkins is equipped with a deadman system, an autoshear syst em, and an additional acoustic backup system for disconnecting and closing the shear rams.

Containment: The experience of gaining control over the Macondo well has resulted in a better understanding of the necessary equipment and syst ems for well containment. As a result, industry and government are better equipped and prepared to day 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 comprehe nsive approach to help prevent and, if needed, control another deepwater control incident. Should the interventions at the well not be possible, specialized equipment can 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 asse mbly and other specialized connection devices will be available from the Marine Well Containment Comp any (MWCC) or other Shell/industry sources and will be specifically addressed in Shell’s NTL No. 2010-N10 submission.

Shell is investing in Research and Development activi ties on its own to identify additional containment components and equipment that will potentially increa se 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 captur e domes”, and 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. . The dynamically positioned ri gs under contract, the Noble Danny Adkins and the Bully 1, will be the preferred rigs for blowout interv ention 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 non-contracted rigs in the GOM could be ut ilized whether for increased expediency or better suitability. All efforts will be made at the time to se cure the appropriate rig. Shell’s current contracted rigs capable of operating at Vito water depths an d reservoir depths without technical constraints are
shown in the Table 4 below:



### Rig Name Rig Type
Noble Danny Adkins Dynamically positioned semi
Noble Bully 1* Dynamically positioned drill ship

Transocean Deepwater Nautilus** Moored semi
Noble Jim Thompson Moored semi Table 4 Shell Contracted Rigs Capable at Vito.

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

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

*Bully 1 estimated arrival October 2011.

**The Transocean Deepwater Nautilus es timated availability is April 2011



### 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. The list of rigs capable of operating at Vi to is tabled above. It is expected to take an average of 14 days to safely secure the well that th e rig is working on up to the point the rig departs location, and an additional three days transit to mo bilize to the relief well site depending on distance to the site. The relief well will take approximately 135 days to drill down to the last casing string above the blowout zone, plus approximately 33 days for precision ranging ac tivity to intersect the blowout well bore. The expected total time to mo bilize and drill a relief well would be 185 days for
Vito.

If a moored rig is chosen to conduct the relief we ll operations, anchor handlers would be prioritized to prepare mooring on the relief well site while the ri g is being mobilized. This mooring activity is not expected to delay initiation of relief well drillin g operations. Shell has three deepwater anchor handlers, the Laney, Dino, and Ross Chouest, on lo ng term contract to su pport its moored rigs.

It is not possible to drill relief wells from any ex isting platforms (ATP’s Titan Platform) due to rig capability limitations and a distance of over 4 miles to the Vito well.

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

blowout.

Shell believes that the best way to manage blowou ts is to prevent them from happening. Detailed below are the measures employed by Shell with the goal of no harm to people or the environment. The Macondo incident has highlighted the importance of these practices. The lessons learned from the investigation are, and will continue to be, incorporated into our operations.Standards: Shell’s well design and operations adhere to internal corporate standards, the Code of Federal Regulations, and industry standards. A robu st management of change process is in place to handle un-defined or exception situations. Ingrai ned in the Shell standards for well control is the philosophy of multiple barriers in the well design and operations on the well.

Risk Management: Shell believes that prevention of major incidents is best managed through the systematic identification and mitigation process (S afety Case). The Safety Case requirement is ingrained into Shell’s Health, Security, Safety , Environment, and Social Performance Control Framework. 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 (i nternal and external) to examine the well design at the conceptu al and detailed design stages for robustness before making a recommendation to the management review board. Sh ell’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 Notices to Le ssees. Shell works closely with rig contractors to ensure proper upkeep of all rig equipment, which me ets or exceeds the strictest of Shell, industry, or regulatory requirements. Well tangibles are govern ed by our internal quality assurance/control standards and industry standards.

MWD/LWD/PWD Tools: Shell intends to use these tools at Vito. 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 wire line logs. Data from the tools are monitored and interpreted real time against pr ognosis 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 hydr ocarbons. The mud logging personnel are in close communication with both the drilling foreman an d 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, petrophysicist s, well engineers, and 24/7 monitoring specialists.
The same real time well control indicators moni tored 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 Internatio nal Association of Drilling Contractors (IADC) and International Well Control Forum (IWCF) are also mandated. Progressions have elements of competency and Shell continues to have comprehensive internal training programs. The best systems and processes can be defeated by lack of knowledge and/or improper values. We believe that a combination of HSE tools (e.g. stop work, pre-job analysis, behavior based safety, DWOPs, audits), management HSE involvement and enforcement (e.g. compliance to life saving rules) have created a strong safety culture in our operations.

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

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

The WCCP specifically addresses implementing acti ons at the emergency site that will ensure personnel safety, organizing personnel and thei r roles in the response, defining information requirements, establishing protocols to mobilize spec ialists 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 we ll drilling, strategy and guidelines, intervention techniques and equipment, site safety mana gement, exclusion zones, and re-boarding.

As set forth in 3f of this document, Shell is cu rrently analyzing recent advances in containment technology and equipment and will incorporate them as they become available.

k) Arrangements for drilling a relief well

The size of the Shell contracted rig fleet in th e GOM from 2010-2015 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 thei r 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

The NTL No. 2010-N06 Worst Case Discharge for Shells Regional Oil Spill Response Plan, highest subsea well, was previously submitted August 1, 2011.

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 an exploration well blowout. Shell’s program is developed to fully satisfy federal oil spill planning regulations. The Regional OSRP pres ents specific information on the response program that includes a description of personnel and equi pment mobilization, the incident management team organization, and the strategies and tactics used to implement effective and sustained spill containment and recovery operations.SECTION 3: Geological & Geophysical Information

A. Geological description

Omitted from Public Information Copies.

B. Structure contour maps.

Omitted from Public Information Copies

.

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

Omitted from Public Information Copies.

Geological Structure Cross-section(s)

Omitted from Public Information Copies

E. Shallow Hazards Report – see below

F. Shallow Hazards Assessment

History

Shell previously received approval to drill Proposed Loca tions D, E, F, and G. Shell then added Proposed Locations I, J, and K but has not received approval to drill. On May 25, 2011, the BOEM required Shell comply with current NTL2009-G40 to protect deepwater be nthic communities. To co mply, Shell is updating its exploration plans and certifying its distance from said benthic communities.

Shallow Hazards Assessment

GEMS prepared a Geologic, Stratigraphic, and Arch eological Assessment on Blocks 940, 984, and 985 of Mississippi Canyon in October 2007 for Shell. The pr oject number is 0507-1331. C&C Technologies conducted an Archeological Assessment Report for Shell in October 2007 on Mississippi Canyon Blocks 895-898, 939- 942, and 983-986. The job number is 072657-072954. The archeological survey detected 106 unidentified sidescan sonar targets, several drag scars, and geolog ical features within the survey. There were no sonar contacts with acoustic signature that require archeo logical avoidance or further investigation. Anadarko previously drilled Well #1 in MC 984. The well is cent ered at X = 941,637; Y= 10,168,473. Shell now requests approval to drill Proposed Locations No. 1 ST (Formerly H), D, E, F, G, I, IS T, J, and K using the DP vessel Noble Danny Adkins. (There are no anchors associated with this Plan.) Fluid expulsion features will be avoided by at least 250’, sonar contacts will be avoided by 50’. There are no flowlines in the vicinity of the proposed locations.

Archeological Statement

Per the archeological assessment report, there are no recommended avoidance areas. Nevertheless, Shell
will avoid all unidentified sonar co ntacts by at least 50 ft.

Proposed Locations:

MC 984 Proposed Location D

X = 943,325 5075’ FEL Y = 10,162,025 7255’ FNLProposed Location D will be positioned in a water dept h of approximately -4097‘. Proposed Location D will be positioned west of the major graben that trends no rth-south through the area. There is no evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proposed Location D. Proposed Location D will not disturb an y high-density areas of chemosynthetic communities.

MC 985 Proposed Location E

X = 959,981 6259’ FEL Y = 10,168,020 1260’ FNL

Proposed Location E will be located in a water depth of approximately -4164’. Proposed Location E will be located southeast of seafloor faults identified 400’, 890’, and 1090’ away. There are no indications of seafloor or near-surface fluid expulsion features or amplitudes identified on side-scan sonar or sub-bottom profiler data. There is no other evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proposed Location E. Proposed Location E will not disturb any highdensity areas of chemosynthetic communities.

MC 985 Proposed Location F

X = 958,996 7244’ FEL Y = 10,166,374 2906’ FNL

Proposed Location F will be located in a water depth of approximately -4,136’. A seafloor fault is identified 480’ northwest of Proposed Location F. Other faults are identified 1,510’ to the southeast and 1400’ to the southwest of Proposed Location F. There are no indi cations of seafloor or near-surface fluid expulsion features or amplitudes identified on side-scan sonar or sub-bottom profiler data. There is no other evidence of seafloor or near-surface faulting, slumping, amplit udes or fluid expulsion features in the vicinity of Proposed Location F.

MC 984 Proposed Location G

X = 941,108 6808’ FWL Y = 10,168,532 748’ FNL

Proposed Location G will be located in a water depth of approximately -4044’. Proposed Location G will be positioned west of the major graben that trends nort h-south through the area. There is no evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proponed
Location G.

MC 984 Rig Center for Locations I, J, K:

X= 942,153 7,563’ FWL Y=10,169,281 1’ FNL

The water depth at rig center is approximately -4,000’. There are no seafloor faults within 1,500’ of rig center. There are no amplitudes or fluid expu lsion features within 2,000’ of rig center.

MC 940 Proposed Location I:

X= 942,769 8,209’ FWL Y= 10,170,010 730’ FSL

The water depth at Proposed Location I is -3,978’. The se afloor slopes to the southwest at a gradient of 1.6° on a relatively featureless ramp. The closest uni dentified side-scan sonar targets numbers 386 and 276 are approximately 3,000’ to the northwest and 2,900’ to th e northeast, respectively. The archeologist did not designate any special avoidance for these. (C&C Techno logies, 2007) Previously drilled MC984 #1 is located 1,900’ southwest of the proposed location. The Crosby Field is to the northeast in MC 898 and 899. The platform, flowlines, and pipelines associated with the Cros by field are over 10 miles from Proposed Location I.
The nearest seafloor fault to the loca tion is approximately 1,000’ east of the proposed location. The proposed well will intersect a small fault at 676’ bml. The casing program will be designed to minimize flow potential.MC 940 Proposed Location J:

X= 942,926 8,366’ FWL Y= 10,169,782 502’ FSL

The water depth at the proposed location is -3,978’. Th e seafloor slopes to the southwest at a gradient of 1.3° on a relatively featureless ramp. The closest unidentified side-scan sonar targets numbers 386 and 276 are approximately 3,300’ northwest an d 3,050’ northeast, respectively. Th e archeologist did not designate any special avoidance for these. (C &C Technologies, 2007) Previously drilled MC984 #1 is located 1,850’ southwest of the proposed location. The Crosby Fiel d is to the northeast in MC 898 and 899. The platform, flowlines, and pipelines associated with the Crosby field are over 10 miles from Proposed Location J. The nearest seafloor fault to the location is approximately 1,000’ east of the proposed location. The proposed well will intersect a small fault at 644’ bml. The casing program will be designed to minimize flow potential.

MC 984 Proposed Location K:

X= 941,218 6,658’ FWL Y=10,168,804 476’ FNL

The water depth at the proposed location is -4,025’. Th e seafloor slopes to the so uthwest at a gradient of 1.5° on a relatively featureless ramp. Previously drilled MC984 #1 is located 520’ southeast of Proposed
Location K. The closest unidentified sidescan sona r target number 386 is approximately 4,500’ to the
northwest. Unidentified sona r target 276 is 4,900’ northeast of the pr oposed location. The archeologist did not designate any special avoidance for these. (C&C Technologies, 2007) The Crosby Field is to the northeast in MC 898 and 899. The platfo rm, flowlines, and pipelines associated with the Crosby field are over 10 miles from Proposed Location K. There are no sea floor faults within 1,500’ of the proposed location. There are no shallow faults that intersect the propos ed well. The casing program will be designed to minimize flow potential.

General Statements

Based on a high-resolution geophysical survey consisti ng of deep-towed Side sc an Sonar and Sub-Bottom Profiler, Sparker, Mini-Sparker, Frequency Enhanced 3- D seismic, Enhanced Surface Renderings (ESRs) and ESRs with amplitudes applies, MC 984, Proposed Location D, E, F, G and No. 1 ST (H) appear suitable for the planned activity.

Based on evaluation of 3-D exploration seismic data wi th high resolution AUV data, multibeam echosounder, side-scan sonar, and subbottom profile r data, amplitude, and amplitude Enhanced Surface renderings, the rig center and Proposed Locations I, IST, J, and K appear suitable for the proposed activities.

Larry Gibson Vernessa Bradford Senior Staff Geologist Shallow Hazards InterpreterG. High-Resolution Seismic Lines

Seismic omitted from Public Inform ation Copies. See attached ESR.

H & I Stratigraphic Column with Time vs depth table

Omitted from Public Information CopiesSECTION 4: Hydrogen Sulfide

A. Concentration

0 ppm.

B. Classification

Based on CFR 250.490 (c), SOI requests that the Region al Supervisor, Field Operations, determine the zones in the proposed drilling operations in this plan to be classified as an area where the absence of H 2 S has been
confirmed.

C. H 2 S Contingency Plan In accordance with 30 CFR 250.490(f) a Continge ncy Plan was not required for this Lease.

D. Modeling Report

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

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

ANCHOR CLEARANCE AND CHEMOSYNTHETIC
ORGANISMS COMMENTS

History

GEMS prepared a Geologic, Stratigraphic, and Arch eological Assessment on Blocks 940, 984, and 985 of Mississippi Canyon in October 2007 for Shell. The project number is 0507-1331.

C&C Technologies conducted an Archeological Assessm ent Report for Shell in October 2007 on Mississippi Canyon Blocks 895-898, 939-942, and 983- 986. The job number is 072657-072954.

The archeological survey detected 106 unidentified sidescan sonar targets, several dr ag scars, and geological features within the survey. There were no sonar contacts with acoustic signature that require archeological avoidance or further investigation.

Shell previously drilled Well #1 in MC 984. The well is centered at X = 941,637 Y 10,168,473. Shell now requests approval to drill Proposed Loca tions D, E, F, G, No 1 ST (Fromer ly H) I, IST J, and K using the DP vessel Danny Adkins or similar rig. Shell had approval fo r a 15,500 ft radius to drill Well # 1. Shell plans to use the approved radius but will maintain a 1,000 ft buffer and not set anchors beyond 14,500 ft. The proposed locations are within that radius, thus, no change is requested.

There are no flowlines in the vicinity of the proposed locations.

Chemosynthetic Community Statement

Per MMS NTL No. 2009-G40, Deepwater Benthic Communities, Attachment A
ASSOCIATED ANCHORS – NO ANCHOR DISTURBANCES WITHIN 250’ OF CHEMOSYNTHETIC COMMUNITIES

For the proposed locations D, E, F, G, No 1 ST (Formerly H), I, IST, J, and K:
Shell will observe the following separation distances from high-density deepwater benthic communities:

1. At least 2,000’ from each proposed muds and cuttings discharge location; and

2. At least 250’ from the location of all other proposed seafloor disturbances (including those caused by anchors, anchor chains, wire ropes, seafloor templa te installation, and pipeline construction). Seafloor disturbances include all “temporary ” disturbances caused during mooring operations (e.g., anchor deployment, setting, and retrieval) as well as those caused by anchoring activities conducted prior to a MODU arriving on location (e.g., pre-installation of suction piles and cables; where seafloor impacts are much greater while the cables are located on the seafloor prior to being pulled taut and attached to the MODU).

Currently, there are no pipelines in the vicinity of Proposed Locations D, E, F, G, No 1 ST (Formerly H) I, IST, J, and K. Previously drilled wellsites in the vicinity in clude Shell’s MC 985 No. 1, Exxon’s MC 941 No. 1, and
ATP’s MC 941 No. 1 and No. 2 wellsites.

Proposed Locations MC 984 Proposed Location D X = 943,325 5075’ FEL Y = 10,162,025 7255’ FNL

Proposed Location D will be positioned in a water depth of approximately -4097‘. Proposed Location D will be positioned west of the major graben that trends nort h-south through the area. There is no evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proposed Location D. Proposed Location D will not disturb an y high-density areas of chemosynthetic communities.MC 985 Proposed Location E X = 959,981 6259’ FEL Y = 10,168,020 1260’ FNL

Proponed Location E will be located in a water depth of approximately -4164’. Proposed Location E will be located southeast of seafloor faults identified 400’, 890’, and 1090’ away. There are no indications of seafloor or near-surface fluid expulsion features or amplitudes identified on side-scan sonar or sub-bottom profiler data. There is no other evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proposed Location E. Proposed Location E will not disturb any highdensity areas of chemosynthetic communities.

MC 985 Proposed Location F X = 958,996 7244’ FEL Y = 10,166,374 2906’ FNL

Proposed Location F will be located in a water depth of approximately -4,136’. A seafloor fault is identified 480’ northwest of Proposed Location F. Other faults are identified 1,510’ to the southeast and 1400’ to the southwest of Proposed Location F. There are no indi cations of seafloor or near-surface fluid expulsion features or amplitudes identified on side-scan sonar or sub-bottom profiler data. There is no other evidence of seafloor or near-surface faulting, slumping, amplit udes or fluid expulsion features in the vicinity of Proposed Location F.

MC 984 Proposed Location G X = 941,108 6808’ FWL Y = 10,168,532 748’ FNL

Proponed Location G will be located in a water depth of approximately -4044’. Proposed Location G will be positioned west of the major graben that trends nort h-south through the area. There is no evidence of seafloor or near-surface faulting, slumping, amplitudes or fluid expulsion features in the vicinity of Proponed
Location G.

MC 984 Rig Center for Locations I, J, K: X= 942,153 7,563’ FWL Y=10,169,281 1’ FNL

The water depth at rig center is appr oximately -4,000’. There are no sea floor faults within 1,500’ of rig center. There are no amplitudes or fluid expu lsion features within 2,000’ of rig center.

MC 940 Proposed Location I: X= 942,769 8,209’ FWL Y= 10,170,010 730’ FSL

The water depth at Proposed Location I is -3,978’. The se afloor slopes to the southwest at a gradient of 1.6° on a relatively featureless ramp. The closest uni dentified side-scan sonar targets numbers 386 and 276 are approximately 3,000’ to the northwest and 2,900’ to th e northeast, respectively. The archeologist did not designate any special avoidance for these. (C&C Techno logies, 2007) Previously drilled MC984 #1 is located 1,900’ southwest of the proposed location. The Crosby Field is to the northeast in MC 898 and 899. The platform, flowlines, and pipelines associated with the Cros by field are over 10 miles from Proposed Location I.
The nearest seafloor fault to the loca tion is approximately 1,000’ east of the proposed location. The proposed well will intersect a small fault at 676’ bml. The casing program will be designed to minimize flow potential.

MC 940 Proposed Location J: X= 942,926 8,366’ FWL Y= 10,169,782 520’ FSL

The water depth at the proposed location is -3,978’. Th e seafloor slopes to the southwest at a gradient of 1.3° on a relatively featureless ramp. The closest unidentified side-scan sonar targets numbers 386 and 276 are approximately 3,300’ northwest an d 3,050’ northeast, respectively. Th e archeologist did not designateany special avoidance for these. (C &C Technologies, 2007) Previously drilled MC984 #1 is located 1,850’ southwest of the proposed location. The Crosby Fiel d is to the northeast in MC 898 and 899. The platform, flowlines, and pipelines associated with the Crosby field are over 10 miles from Proposed Location J. The nearest seafloor fault to the location is approximately 1,000’ east of the proposed location. The proposed well will intersect a small fault at 644’ bml. The casing program will be designed to minimize flow potential.

MC 984 Proposed Location K: X= 941,218 6,658’ FWL Y=10,168,804 476’ FNL

The water depth at the proposed location is -4,025’. Th e seafloor slopes to the so uthwest at a gradient of 1.5° on a relatively featureless ramp. Previously drilled MC984 #1 is located 520’ southeast of Proposed
Location K. The closest unidentified sidescan sona r target number 386 is approximately 4,500’ to the
northwest. Unidentified sona r target 276 is 4,900’ northeast of the pr oposed location. The archeologist did not designate any special avoidance for these. (C&C Technologies, 2007) The Crosby Field is to the northeast in MC 898 and 899. The platfo rm, flowlines, and pipelines associated with the Crosby field are over 10 miles from Proposed Location K. There are no sea floor faults within 1,500’ of the proposed location. There are no shallow faults that intersect the propos ed well. The casing program will be designed to minimize flow potential.

General Statements

Based on a high-resolution geophysical survey consisti ng of deep-towed Side sc an Sonar and Sub-Bottom Profiler, Sparker, Mini-Sparker, Frequency Enhanced 3- D seismic, Enhanced Surface Renderings (ESRs) and ESRs with amplitudes applies, MC 984, Proposed Loca tions D, E, F, G and No. 1 ST (Formerly H) appear suitable for the planned activity.

Based on evaluation of 3-D exploration seismic data wi th high resolution AUV data, multibeam echosounder, side-scan sonar, and subbottom profile r data, amplitude, and amplitude Enhanced Surface renderings, the rig center and Proposed Locations I, J, and K appear suitable for the proposed activities.

Larry Gibson Vernessa Bradford Senior Staff Geologist Shallow Hazards Interpreter

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 st atement (shunting), Live bottoms, (Pinnacle Trend) map, Live bottoms (low relief ) map, potentially sensitive biological features map.

G. Remotely Operated Vehicle (ROV) Monitoring Plan

In accordance with the provisions of NTL No. 2008-G06, Remotely Operated Vehicle Surveys in Deepwater, Mississippi Canyon 940, 984 and 985 are all located in Grid 13. Grid 13 is an area that has adequate ROV survey coverage; therefore we are not proposing to run the pre and post ROV survey in accordance with the NTL.

H. Threatened and Endangered Species Information

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

Common Name Scientific Name T/E Status

Hawksbill Turtle Eretmochelys imbricata E

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

Leatherback Turtle Dermochelys coriacea E Loggerhead Turtle Caretta caretta TThere are 29 species of marine mammals that may be found in the Gulf of Mexico (see table). 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

The EIA, EP Attachment 18, discusses potential impacts and mitigation measures related to threatened and endangered species.

I. Air and Water Quality Information

Pursuant to NTL No. 2008-G04 the prop osed 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.

J. Socioeconomic Information

Pursuant to NTL No. 2008-G04 the prop osed operations covered by this EP do not require Shell to provide additional information relating to air and water qualit y information. For specific information relating to socioeconomic information please refer to the EIA, Attachment 18.SECTION 7: Waste and Discharge InformationA.Discharge to GOM or DownholeNote: Please specify if the amount reported is a total or per well amountSupplmental EP - MC 940, 984 and 985Type of Waste and Composition Composition Projected Amount Discharge rate Discharge Method Answer yes or noWill drilling occur ? If yes, you should list muds and cuttingsEXAMPLE: Cuttings wetted with ynthetic based fluidCuttings generatedwhile using syntheticbased drilling fluid. X bbl/well X bbl/day discharge pipe NoWater-based drilling fluid barite,additives, mud 35,000 bbl/well 17,500 bbls /day discharge overboard NoCuttings wetted with water-based fluidcuttings coated with water based drillingmud 3,180 bbls/well 795 bbls /day discharge overboard NoCuttings wetted with synthetic-based fluidCuttings generated while using syntheticbased drilling fluid. 13,700 bbls/well 275 bbls /day discharge overboard NoWill humans be there? If yes, expect conventional wasteEXAMPLE: Sanitary waste waterX liter/person/day NA chlorinate and discharge NoDomestic waste (kitchen water, shower water) grey water 160 bbls/day NAGrinded to less than 25 mm mesh sizeand discharge overboard NoSanitary waste (toilet water) treated sanitary waste 100 bbls/day NATreated in the MSD** prior to dischargeto meet NPDES limits NoIs there a deck? If yes, there will be Deck DrainageDeck DrainageContaminated wash and rainwater3,900 bbls / well 20 bbls / dayDrained overboard through deckscuppers NoWill you conduct well treatment, completion, or workover?well treatment fluids NA NA NA NA Nowell completion fluids NA NA NA NA Noworkover fluids NA NA NA NA NoMiscellaneous discharges. If yes, only fill in those associated with your activity.Desalinization unit discharge Rejected water from watermaker unit 74,100 bbls / wellNoBlowout prevent fluid Water based 400 bbls/well 0.2 bbls /day Subsea BOP @ seafloor NoBallast water Uncontaminated seawater 390,000 bbls / well 2,6890 bbls / day discharge overboard NoBilge waterBilge and drainage water will be treated toMARPOL standards (< 15ppm oil in water). 390,000 bbls / well 2,6890 bbls / dayBilgeanddrainagewaterwillbetreatedto MARPOL standards (< 15ppm oil inwater). NoExcess cement at seafloor Cement slurry246 bbls/well (assume planned100% excess is discharged) 246 bbls /daydischarged through shunt line, 77' belowwaterline NoFire water Treated seawater 11,000 bbls / well 2,000 bbls / month scuppers NoCooling water Treated seawater 23,295,000 bbls / well 456,343 bbl/day/welldischarged through shunt line, 77' belowwaterline NoWill you produce hydrocarbons? If yes fill in for produced water.Produced water NA NAWill you be covered by an individual or general NPDES permit ?GENERAL PERMITGMG290103NOTE: 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 TOTHE GOMProjectedDownholeDisposalProjected generated waste Projected ocean dischargesB. Landfill, inject, incinerate or recycle table

C. Modeling Report

Shell did not model the trajectory for discharg es because it is not required in the GOM. Supplmental EP - MC 940, 984 and 985

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, Fourchon, LA 120 bbls/day Recycled Cuttings wetted with Water-based fluid NA NA NA NA NA Cuttings wetted with Synthetic-based fluid NA NA NA NA NA 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 Managmenet, W. Patterson, LA or ARC, New Iberia, LA 200 lbs/month recylce

Trash and debris - non-recyclables trash and debris storage bins on supply boat Republic/BFI landfill, Sorrento, LA or the parish landfill, Avondale, LA 400 lbs/month landfill

Used oil and glycol used oil

, oily rags and pads, empty drums and cooking oil drums on supply boat Omega Waste Managmenet, W. Patterson, LA or ARC, New Iberia, LA 20 bbls/month recycled

Hazardous Waste paints, solvents and unused chemicals drums on supply boat Safety Kleep, Denton, TX 60 bbls/mo recycled

Universal Waste Items Batteries, lamps, glass and mercury-contaminated

waste drums on supply boat Lamp Environmental, Hammond, LA 50 bbls/mo 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 wasteSECTION 8: AIR EMISSIONS INFORMATION

A. Emissions Worksheet and Screening Questions

Screening Questions for EP’s Yes No

Is any calculated Complex Total (CT) Emi ssion amount (in tons) associated with your proposed exploration activities morethan 90% of the amounts calculated using the following formulas: CT = 3400D 2/3 for CO, and CT 33.3D for the other air pollutants (where D distance to shore in miles)? x

Do your emission calculations include any emission reduction measures or
modified emission factors? x Are your proposed exploration activities located east of 87.5° W longitude? x Do you expect to encounter H 2 S at concentrations greater than 20 parts per million (ppm)? x
Do you propose to flare or vent natura l 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 informatio n is compiled on the summary form of the two
sets of worksheets. You can submit either thes e summary forms or use the format below. You
do not need to include the entire set of worksheets.

Air Pollutant Plan
Emission 1

Amounts

(tons) Calculated Exemption 2

Amounts

(tons) Calculated Complex Total
Emission
Amounts 3

(tons)

PM
SO x NOx
VOC
CO

1 For activities proposed in your EP or DOCD, list th e projected emissions calculated from the worksheets. 2 List the exemption amounts for your proposed activities calculated by using the form ulas in 30 CFR 250.303(d). 3 List the complex total emissions associated with your proposed activities calculated from the worksheets

2) Contact: Sylvia Bellone, (504) 728-7215, Sylvia.Bellone@shell.com

(1) Worksheets

Worksheets are attached.AIR QUALITY SCREENING CHECKLISTOMB Control No. 1010-0049OMB Approval Expires: August 31, 2006COMPANYShell Offshore IncAREAMississippi CanyonBLOCK940, 984 & 985LEASEG31534, G22919 & G22920PLATFORMVitoWELLD,E,F,G,I(+st),J,K, ST at Well 1 (H Surface Location)COMPANY CONTACTSylvia BelloneTELEPHONE NO.504-728-7215REMARKSREMARKSLEASE TERM PIPELINE CONSTRUCTION INFORMATION:YEAR NUMBER OFTOTAL NUMBER OF CONSTRUCTION DAYSPIPELINES19992000200120022003200420052006200720082009-2014Form MMS-139 (August 2003)AIR EMISSION CALCULATIONSOMB Control No. 1010-0049OMB Approval Expires: August 31, 2006COMPANY AREA BLOCK LEASE PLATFORM WELLShell Offshore Inc Mississippi Canyon 940, 984 & 985G31534, G22919 &G22920VitoD,E,F,G,I(+st),J,K, STat Well 1 (H SurfaceLocation)Emitted SubstanceYearPM SOx NOx VOC CO2011-2018 33.83 154.58 1158.88 34.90 252.84Allowable2231.10 2231.10 2231.10 2231.10 56086.99COMPANY AREA BLOCK LEASE PLATFORM WELLShell Offshore Inc Mississippi Canyon 940, 984 & 985G31534, G22919 &G22920VitoD,E,F,G,I(+st),J,K,ST at Well 1 (HSurface Location)Basis for various estimates Used in this AQRScheduleSchedule is as below.ProposedActivity StartDate EndDate No.ofDaysDrill Well G9/30/2012 2/22/2013145Drill Well F9/30/2013 2/22/2014145Drill Well E9/30/2014 2/22/2015145Drill Well D9/30/2015 2/22/2016145Drill Well K9/29/2017 2/21/2018145Sidetrack Well 1 (H surface location drilled)9/29/2018 12/3/201865Many cells are linked or are used as links in other sheets- change cell contents OR add/delete rows/columnswithcaution!TentativeScheduleofProposedActivitiesDrill Well I & ST 10/1/2011 4/28/2011 210Drill Well J9/29/2016 2/21/2017145For conservatism (and simplicity given that individual wells will be drilled across calender years) in completing the AQR, assume 210 daysper calender year of drilling160111A1.msgpercalenderyearofdrilling.160111A1.msgCOMPANY AREA BLOCK LEASE PLATFORM WELLShell Offshore Inc Mississippi Canyon 940, 984 & 985G31534, G22919 &G22920VitoD,E,F,G,I(+st),J,K,ST at Well 1 (HSurface Location)Basis for various estimates Used in this AQRMany cells are linked or are used as links in other sheets- change cell contents OR add/delete rows/columnswithcaution!Noble Danny Adkins main Engine Operating scenarios (Modes)per embedded emailScenario 1 – Riser less drilling (top hole)Four engines online @ 35 to 45%Scenario 2 - Riser less drilling Running casing/ cementingFour Engines online @ 30 to 40 %Scenario 3 - Transit (5 knot log speed)Four engines online @ 65%Scenario 4 – Drilling ahead with BOP deployedFour Engines online @ 40 to 50%Engine Op Mode 1 Op Mode 2 Op Mode 3Op Mode 41 45 40 65502 45 40 65503 45 40 65504 45 40 65505 00 006 00 00% LoadEB112514.msg7 00 008 00 00Frequency of scenario occurrence inCampaign, % 0 0 10 90Individual Eng HP, nameplate 6169 6169 6169 6169Total HP delivered from all 8 engines inCampaign, by scenario0 0 1603.94 11104.2Average % Load delivered from eachenginein Campaign 0.0% 0.0% 3.3% 22.5%25.8%Given Mode 3 and 4 are highest load modes, assume rig operates in mode 3 (transit) 10% of time andremainder in Mode 4 (90% of time as a conservative estimate for emissions)For simplification, the above average % loads are added to arrive at a single Overall Operating Mode (Load Factor) for allEngine loads will vary from above: the % shown is the AVERAGE thru-out the campaign for each engine and is used to estimateANNUAL emissionsCOMPANY AREA BLOCK LEASE PLATFORM WELLShell Offshore Inc Mississippi Canyon 940, 984 & 985G31534, G22919 &G22920VitoD,E,F,G,I(+st),J,K,ST at Well 1 (HSurface Location)Basis for various estimates Used in this AQRMany cells are linked or are used as links in other sheets- change cell contents OR add/delete rows/columnswithcaution!Support Vessel EmissionsRiserless10days3OSVsperday@9440HPEA.30CrewBoatsperday@5400HPDeepening200days1OSVaverageonlocation@9440HP.30CrewBoatsperday@5400HPThe above data is tabulated as follows and used inthe AQR:Equipment HP Rating Hr/day Duration/year(Days)Riserless Support vessel OSV (>600 hp) 9440 24 10Riserless Support vessel OSV (>600 hp) 9440 24 10Riserless Support vessel OSV (>600 hp) 9440 24 10On average one vessel withn 25 miles at any give time. Shellpolicy restricts D/P to < 50% near rig. When in standby awayfrom rig but within 25 miles load wil be < 50% (conserve fuel).When transitinginto/out of 25 miles, vessels can be restrictedto <50% loadOn average one vessel withn 25 miles at any give time. Shellpolicy restricts D/P to < 50% near rig. When in standby awayfrom rig but within 25 miles load wil be < 50% (conserve fuel).When transitinginto/out of 25 miles, vessels can be restrictedOn average one vessel withn 25 miles at any give time. Shellpolicy restricts D/P to < 50% near rig. When in standby awayfrom rig but within 25 miles load wil be < 50% (conserve fuel).When transitinginto/out of 25 miles, vessels can be restrictedto <50% loadComment6C3E8FDB.msgRiserless Support vessel Crew Boat (>600 hp) 5400 8 10Deepening Support vessel OSV (>600 hp) 9440 24 200Deepening Support vessel Crew Boat 5400 8 200Becauise of the 50% load limits, set all supportvessel load factors =50%MiscellaneousAssume emergency diesel is tested for 1 hr/week = 210 days/7 days = 30 weeks = 30 days per campaign testing occursAssume cement units are used 7.5% of the time during deepening = 0.075 *200 =15days per campaignOn average crew vessels will be within 25 miles 30% of time.To model this set hr/d=8. Shell policy restricts D/P to < 50%near rig. When in standby away from rig but within 25 milesload wil be < 50% (conserve fuel). When transiting into/out of25 miles, vessels can be restricted to <50% loadOn average one vessel withn 25 miles at any give time. Shellpolicy restricts D/P to < 50% near rig. When in standby awayfrom rig but within 25 miles load wil be < 50% (conserve fuel).When transitinginto/out of 25 miles, vessels can be restrictedto <50% loadOn average crew vessels will be within 25 miles 30% of time.To model this set hr/d=8. Shell policy restricts D/P to < 50%near rig. When in standby away from rig but within 25 milesload wil be < 50% (conserve fuel). When transiting into/out of25 miles, vessels can be restricted to <50% loadWhentransitinginto/outof25miles,vesselscanberestrictedto <50% loadAIR EMISSIONCOMPUTATION FACTORSFuel Usage Conversion FactorsNatural Gas Turbines Natural Gas Engines Diesel Recip. EngineREF.DATESCF/hp-hr 9.524 SCF/hp-hr 7.143 GAL/hp-hr 0.0483AP42 3.2-14/76 & 8/84Equipment/Emission Factorsunits PM SOx NOx VOC CO REF. DATENG Turbines gms/hp-hr 0.00247 1.3 0.01 0.83AP42 3.2-1& 3.1-110/96NG 2-cycle leangms/hp-hr0.00185 10.9 0.431.5AP42 3.2-110/96NG 4-cycle leangms/hp-hr0.00185 11.8 0.721.6AP42 3.2-110/96NG 4-cycle richgms/hp-hr0.00185 100.148.6AP42 3.2-110/96Diesel Recip. < 600 hp.gms/hp-hr 1 1.468 141.12 3.03AP42 3.3-110/96Diesel Recip. > 600 hp.gms/hp-hr 0.32 1.468 110.332.4AP42 3.4-110/96Diesel Boilerlbs/bbl 0.084 2.42 0.84 0.008 0.21AP42 1.3-12,149/98NG Heaters/Boilers/Burners lbs/mmscf 7.6 0.593 1005.584AP42 1.4-1, 14-2, & 14-3 7/98NG Flareslbs/mmscf0.593 71.4 60.3 388.5AP42 11.5-19/91Liquid Flaringlbs/bbl 0.42 6.83 20.01 0.21AP42 1.3-1 & 1.3-39/98Tank Vaporslbs/bbl0.03E&P Forum1/93Fugitiveslbs/hr/comp.0.0005API Study12/93Glycol Dehydrator Ventlbs/mmscf6.6La. DEQ1991Gas Ventinglbs/scf0.0034Sulfur Content Source Value UnitsFuel Gas3.33 ppmDiesel Fuel0.4 % weightProduced Gas( Flares) 3.33 ppmProduced Oil (Liquid Flaring) 1 % weightForm MMS-139 (August 2003)Page 2 of 8AIR EMISSION CALCULATIONSCOMPANYAREABLOCKLEASEPLATFORM WELLCONTACT PHONE REMARKSShell Offshore Inc Mississippi Canyon940, 984 & 985G31534,G22919 &G22920VitoD,E,F,G,I(+st),J,K,ST at Well 1 (HSurface Location)SylviaBellone504-728-7215OPERATIONSEQUIPMENTRATING MAX. FUEL% Average EngACT. FUEL RUN TIMEMAXIMUM POUNDS PER HOURESTIMATED TONSDiesel EnginesHP GAL/HRGAL/DNat. Gas EnginesHP SCF/HRSCF/DBurnersMMBTU/HR SCF/HRSCF/D HR/D DAYS PM SOx NOx VOC CO PM SOx NOx VOC CODRILLINGPRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16Noble DannyPRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16AtkinsPRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16PRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16PRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16PRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16PRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16PRIME MOVER>600hp diesel6169 297.9627 25.75% 1841.41 24 210 4.35 19.95 149.47 4.48 32.61 2.82 12.94 96.99 2.91 21.16RECIP.>600hp diesel (emergency generator)2549 123.1167 n/a2954.801 30 1.80 8.24 61.76 1.85 13.47 0.03 0.12 0.93 0.03 0.20AUX EQUIP>600hp diesel (cementing unit 1) 200096.6n/a2318.40 24 15 1.41 6.47 48.46 1.45 10.57 0.25 1.16 8.72 0.26 1.90AUX EQUIP<600hp diesel (cementing unit 2) 490 23.667n/a568.0124 15 1.08 1.58 15.11 1.21 3.27 0.19 0.29 2.72 0.22 0.59Riserless Support vessel OSV (>600 hp)9440 455.952 50%5471.42 24 10 6.65 30.52 228.72 6.86 49.90 0.40 1.83 13.72 0.41 2.99Riserless Support vessel OSV (>600 hp)9440 455.952 50%5471.42 24 10 6.65 30.52 228.72 6.86 49.90 0.40 1.83 13.72 0.41 2.99Riserless Support vessel OSV (>600 hp)9440 455.952 50%5471.42 24 10 6.65 30.52 228.72 6.86 49.90 0.40 1.83 13.72 0.41 2.99Riserless Support vessel Crew Boat (>600 hp) 5400 260.82 50%3129.848 10 3.81 17.46 130.84 3.93 28.55 0.08 0.35 2.62 0.08 0.57Deepening Support vessel OSV (>600 hp)9440 455.952 50%5471.42 24 200 6.65 30.52 228.72 6.86 49.90 7.98 36.63 274.47 8.23 59.88Deepening Support vessel Crew Boat5400 260.82 50%3129.848 200 3.81 17.46 130.84 3.93 28.55 1.52 6.98 52.33 1.57 11.42DRILLING OIL BURN000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00WELL TEST GAS FLARE000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00See Sheet"Basisfor estimates"Engine loadswill vary frombelow- the %shown areAVERAGES thruout thecampaign2011-2018 YEAR TOTAL73.30 332.89 2497.65 75.68 544.91 33.83 154.58 1158.88 34.90 252.84EXEMPTIONCALCULATIDISTANCE FROM LAND IN MILES2231.10 2231.10 2231.10 2231.10 56086.9967.0COMPANY AREA BLOCK LEASEPLATFORM WELLShell Offshore Inc Mississippi Canyon 940, 984 & 985 G31534, G22919 & G22920VitoD,E,F,G,I(+st),J,K, ST atWell 1 (HSurfaceLocation)Proposed Limits for EPProposed LimitSource Year Total Fuel Consumed in the Year,galComment Proposed ComplianceAssurance methodEqual to sum of Daily Consumption inColumn F of Emissions spreadsheet timestotal days of drillingin theyearNDA MainEnginesAll years 3,093,568 Limiting total fuel consumed in the period ensuresaverage annual emissions as estimated won't beexceeded (while still allowing for short periods oftime where fuel usage may be higher than the dailyfuel usage from Column F might be exceeded dueto currents, drilling conditions, etc)Maintain logs of fuel consumed byall main engines, and rig location.Retain records through duration ofEP for inspection if requested byBOEM.Source Year Proposed Limit Comment Proposed ComplianceAssurance methodSupportvesselsAll years All vessels will maintain total engineHP less than or equal to 50% designload while within 25 nautical miles ofrig.Since emission estimates assume all vessels are ator below 50% through-out the campaign, limitingloads to 50% or less will ensure average annualemissions are not exceeded in any given year.Maintain logs of all vessel loadsand locations. Retain recordsthrough duration of EP forinspection if requested by BOEMSection 9: OIL SPILL INFORMATION

A. Oil Spill Response Planning

All the proposed activities and facilities in this SEP are 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 BOEMRE October 26, 2010, March 15, 2011, May 31, 2011, July 6, 2011 and August 1, 2011 and is pending approval. An update to the OSRP Certification in accordance with 30 CFR 254.2 was deemed submitted to the BOEMRE August 4, 2011.

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

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

Worst Case Scenario Determination:

Category Regional OSRP EP Type of Activity 1 Drilling Rig Drilling Rig Facility Location (area/block) MC 807 MC 984 Facility Designation 2 Subsea well “A” Subsea well No. 1 (H) Distance to Nearest Shoreline (miles) 53 67

Volume 3 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
314,000** BOPD

314,000 Bbls Type of Oil(s) - (crude oil, condensate, diesel) Crude oil Crude oil

API Gravity(s) 4 26o 25.9o

*24 hour rate (365,000 BOPD 30 day average) **24 hour rate (280,000 BOPD 30 day average)

Footnotes: 1. Types of activities include pipeline, platform, cais son, 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 worstcase discharge volume determined using the guidan ce 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, submitted August 1, 2011, and since the worst-case scenario determined for our EP does not replace the appropriate worst-case scenario in our re gional OSRP, I hereby certify that Shell Offshore Inc has the capability to respond, to the maximum extent pr acticable, 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 Table above and complete discussion in Section 2J.

2) Trajectory Analysis

Trajectories of a spill and the probability of it impacting a land segment have been projected utilizing information in the BOEMRE Oil Spill Risk Analysis Model (OSRAM) for the Central and
Western Gulf of Mexico available on the BOEMRE website using 30 day impact. Offshore areas along the trajectory between the source and land segm ent contact could be impacted. The land segment contact probabilities are shown in Table 9.C.1.

Area/Block OCS-G Launch

Area Land Segment Contact %

Exploratory

MC 984 22919 58 Galveston, TX 1

Jefferson, TX 1

Cameron, LA 3

Vermilion, LA 2

Iberia, LA 1

Terrebonne, LA 3

Lafourche, LA 3

Jefferson, LA 1
Plaquemines, LA 8

St. Bernard, LA 1

Okaloosa, FL 1

Table 9.C.1 Probability of Land Segment Impact

C. Resource Identification

The locations identified in Table 9.C.1 are the highes t probable land segments to be impacted using the BOEMRE Oil Spill Risk Analysis Model (OSRAM ). The environmental sensitivities are identified using the appropriate National Oceanic and Atmo spheric Administration (NOAA) Environmental Sensitivity Index (ESI) maps for the given land se gment. ESI maps provide a concise summary of coastal resources that are at risk if an oil spill o ccurs nearby. Examples of at-risk resources include biological resources (such as birds and shellfish be ds), 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 he lp responders meet one of the main response objectives: reducing the environmental conseq uences 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 econ omic or environmental importance that potentially could be impacted by the Tobago WCD scenario.

Onshore/Nearshore: Plaquemines Parish is identified as the most probable impacted Parish within the Gulf of Mexico for 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. Plaquemines Parish includes two Nation al Wildlife Refuges and one Wildlife Management Area including the Breton National Wildlife Refuge, the Delta National Wildlife Refuge, and the Pass a Loutre Wildlife Management Area. 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 Essentia l 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 Contingenc y Plans (ACPs) were developed to provide a well coordinated response to oil disc harges and other hazardous releas es. The One Gulf Plan is specific to the Gulf of Mexico to advance the unity of po licy 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 Vito Worst Case Discharge as effectively as possible.

Applied Science Associates (ASA) conducted a de epwater blowout simulation for The Response Group to better determine subsurface and surface ev aporation and dispersion rates. Below is a table outlining the applicable evaporation and dispersion quantities:

Mississippi Canyon 940, 984 & 985 Calculations
(BBLS)



### i. 30 Day Average WCD = 280,000 bbls



### ii. Subsurface dispersion – 25% (Water Depth = ~9,500’) -70,000 bbls



### iii. REMAINING WCD AFTER SU BSURFACE DISPERSION 210,000 bbls



### iv. Surface dispersion and evaporation – 25% -52,500 bbls

TOTAL REMAINING ~157,500 bbls

Table 9.D.1 Oil Remaining After Subsurface and Surface DispersionShell 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 Tran srec skimmers are still effective and safe in sea states of 6-8 ft. If sea conditions prohibit safe me chanical recovery efforts, then natural dispersion and airborne chemical dispersant application (vis ibility & 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 reques t 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 pr otection, 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 ti me to the site, and deployment). The Incident Commander or designee may contact other servic e companies if the Unified Command deems such services necessary to the response efforts.

Subsea Control and Containment: Shell, as a founding member of the Marine Well Containment Company (MWCC), will have access to a fully in tegrated subsea well control and containment system 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 will be addre ssed in Shell’s NTL10 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 762,324 barrels/day. Temporary storage associated with the identified skimming and temporary storage equipment equals approximately 606,284 barrels.

De-rated Recovery Rate (bopd) Storage (bbls)
Offshore Recovery 516,021 539,600 Offshore Storage 211,500 Nearshore Recovery 90,263 11,224

Total 606,284 762,324
Table 9.D.3 Mechanical Recovery Combined De-Rated Capability

See attachment 9.D.4 Offshore On -Water Recovery Activation List
See attachment 9.D.5 Offshore On -Water Storage Activation List See attachment 9.D.6 Nearshore On-Water Recovery Activation ListOil Storage: The strategy for transferring, storing and di sposing of oil collected in these recovery zones is to utilize two 150,000-160,000 ton (dead weig ht) tankers mobilized by Shell (or any other tanker immediately available). The recovered oil wo uld 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, mo nitor, and target response to oil spills. Aircraft and spotters can be mobilized within hours of an event.

See attachment 9.D.7 Aerial Surveillance Activation List

Aerial Dispersant: Depending on proximity to shore and wa ter 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 da y. 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 disper sant operations, the CCA’s Aerial Dispersant Delivery System (ADDS) would be mobiliz ed. The ADDS has a dispersant spray capability of 5,000 gallons per sortie.

See attachment 9.D.8 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 mo nitors), skid mounted systems, or purpose-built boom arm spray systems. Vessels can apply dispersa nt within the first 12-24 hours of the response and continually as
directed.

See attachment 9.D.9 Offshore Boat Spray Dispersant Activation List

Subsea Dispersant: Shell has contracted with Wild Well Co ntrol 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, labo ratory tests and field tests will help in facilitating the optimal application rate and effectiveness num bers. For planning purposes, The system has the potential to disperse approximately 24,500 to 34,000 barrels of oil per day.

See attachment 9.D.10 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. IS B services may be provided by the primary OSRO contractors. If appropriate condit ions 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 suppo rt/safety boat would be present during active burning operations to provide logistics, safety an d 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 be fore 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 ma ny factors, recent data suggests that a typical burn might eliminate approximately 750 barrels. Fo r 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 an d remove up to ~12,000 bbl s/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 ma y cause a substantial negative impact on the environment. All safety considerations will be evalua ted. In addition, Shell will assess the situation
and can make notification within 48 hours of th e 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.

See attachment 9.D.11 In-Situ Burn Equipment Activation ListShoreline Protection: If the spill went unabated, shoreline impact in St. Bernard or Plaquemines Parish, LA would depend upon existing environme ntal 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 surveillan ce 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, The Response Group and Unified
Command would be consulted to ensure that envir onmental and special economic resources would be correctly identified and prioritized to ensure optimal protection. The Response Group shoreline response guides 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 allowi ng a more effective response to site-specific
circumstances.

See attachment 9.D.12 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 prot ect and/or rehabilitate wildlife. The resources under contract for the protection and rehabilitation of affected wildlife are in the following table:

See attachment 9.D.12 Shoreline Protection and Wildlife Support List

(9c) Modeling Report

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

Figure 9.C.4 Pass a Loutre West ESI MapFigure 9.C.5 Main Pass ESI MapTable 9.D.4 Offshore On-Water Recovery Activation ListTable 9.D.4 Offshore On-Water Recovery Activation List (continued)Table 9.D.4 Offshore On-Water Recovery Activation List (continued)Table 9.D.4 Offshore On-Water Recovery Activation List (continued)* - These components are additional operational requirements that must be procured by OSROs in addition to the system identifie d. Table 9.D.4 Offshore On-Water Recovery Activation List (continued)Table 9.D.5 Offshore On-Wat er Storage Activation ListTable 9.D.6 Nearshore On-Water Recovery Activation ListTable 9.D.6 Nearshore On -Water Recovery Activation List (continued)Table 9.D.6 Nearshore On -Water Recovery Activation List (continued)Table 9.D.7 Aerial Surveillance Activation ListTable 9.D.8 Offshore Aerial Dispersant Activation ListTable 9.D.9 Offshore Boat Spray Dispersant Activation List

Table 9.D.10 Subsea Dispersant Package Activation ListTable 9.D.11 In-Situ Burn Equipment Activation ListTable 9.D.11 In-Situ Burn Equipment Activation List (continued)Table 9.D.12 Shoreline Protection and Wildlife Support ListSECTION 10: Environmental Monitoring Information

A. Monitoring Systems

A rig based Acoustic Doppler Current Profiler (ADCP) is used to continuously monitor the current beneath the Rig. Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously
monitored

B. Incidental Takes

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

NTL No.2007-G03 “Marine Trash and De bris Awareness and Elimination” NTL No.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

Leases OCS-G 22919, 22920 and 31534 are not part of a Biological Sensitive Area, known Chemosynthetic Area, Military Warning Area or Shipping Fairway. They are designated as having a high potential for containing archeological properties.

SECTION 12: Environmental M itigation Measure Information

A. Impacts to Marine and coastal environments

The proposed action will implement mitigation measur es required by laws and regulations, including all applicable Federal & State requirements concerning ai r 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. The EIA attached as Section 18 to this plan discusses impacts and mitigation measures.

B. Incidental Takes

We do not anticipate any incidental takes related to th e proposed operations. Shell implements the mitigation measures and monitors for incidental takes of protecte d species according to the following notices to lessees and operators from the Minerals Management Service:

NTL No.2007-G03 “Marine Trash and De bris Awareness and Elimination” NTL No.2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species Reporting”

SECTION 13: Related Facilities and Operations Information

Information regarding Related Facilities and Operations In formation, transportation sy stems, & 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 (Bbls) Maximum No. In Area at Any
Time Trip Frequency or
Duration

Noble Danny Adkins Crew Boats 1040 2 Twice per week Offshore Support Vessels 9750 3 145 days/well Helicopter 22 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 9750 1 week Port Fourchon to MC 984

C. Drilling Fluids Transportation 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 Tanks below deck onboard
OSV

D. Solid and Liquid Wastes Transportation

See Table 7B.

E. Vicinity Map – See attached.SECTION 15: Onshore Support Facilities Information

A. General

Name Location Existing/New/Modified

Boothville PHI Heliport Boothville, LA Existing

C-Port II Fourchon, LA Existing

The existing onshore support base for air transportation will be PHI Heliport in Boothville, LA located at 38963 Highway 23. The existing onshore base for installation water traffic will be the Fourchon Terminal located on Bayou LaFourche, south of Leesville, LA approximately thr ee miles from the Gulf of Mexico. Marine support for the drilling operation will be from C-Port II located in Fourchon, LA.

B. Support Base Construction or Expansion

This Section does not apply to this EP as Shell does not plan to cons truct a new onshore support base or expand an existing one to accommodat e 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 cons truct a new onshore support base or expand an existing one to accommodat e the activities proposed in this EP.

D. Waste Disposal

See Table 7B.

SECTION 16: Sulphur Operations Information

Information regarding Sulfur Operations Information is no t included in this EP as such information is only necessary in the case of DOCDs.

SECTION 17: Coastal Zone Manage ment Act (CZMA) Information

Concurrence with Louisiana CZM was obtained in Plan N-9220 for leases OCS-G 22919 and 22920 (filed by Anadarko). Concurrence with Louisiana and Texas CZ M was obtained in Plan N-9383 for Leases OCS-G 22919 and OCS-G 31534 filed by Shell.

### SECTION 18: Environmental Impact Analysis (EIA)

See following report prepared by CSA.

# Environmental Impact Analysis

SUPPLEMENTAL EXPLORATION PLAN Mississippi Canyon Block 940 (OCS-G 31534) Mississippi Canyon Block 984 (OCS-G 22919) Mississippi Canyon Block 985 (OCS-G 22920)

Offshore Louisiana

May 2011

Prepared for:

Sylvia Bellone
Shell Offshore Inc.

P.O. Box 61933 New Orleans, Louisiana 70161 Telephone: (504) 728-7215

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue Stuart, Florida 34997 Telephone: (772) 219-3000Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page ii 

# CONTENTS

Page



## Introduction ......................................

................................................... ....................... 1 Project Summary ...................................

................................................... .......................................... 1 Purpose of the EIA ................................

................................................... ........................................... 1 OCS Regulatory Framework ..........................

................................................... ................................... 3 Oil Spill Prevention and Contingency Planning .....

................................................... ............................ 5 EIA Organization ..................................

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



## A. Impact-Producing Factors ......................

................................................... .............. 6 A.1 Drilling Rig Presence (including noise and ligh ts) ............................................... ......................... 6 A.2 Physical Disturbance to the Seafloor ..........

................................................... ............................. 6
A.3 Air Pollutant Emissions .......................

................................................... .................................... 9 A.4 Effluent Discharges ...........................

................................................... ...................................... 9
A.5 Water Intake ..................................

................................................... ........................................ 9 A.6 Onshore Waste Disposal ........................

................................................... ............................... 10
A.7 Marine Debris .................................

................................................... ...................................... 10 A.8 Support Vessel and Helicopter Traffic .........

................................................... .......................... 10
A.9 Accidents .....................................

................................................... ......................................... 11 A.9.1 Types of Accidents Evaluated ................

................................................... .................... 11 A.9.2 Small Fuel Spill ............................

................................................... .............................. 11 A.9.3 Crude Oil Spill (Worst Case Discharge) ......

................................................... ................. 12 A.9.4 Other Accidents Not Analyzed in Detail ......

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



## B. Affected Environment ..........................

................................................... .............. 16

C. Impact Analysis ...............................

................................................... ................... 18 C.1 Physical/Chemical Environment .................

................................................... ........................... 18 C.1.1 Air Quality .................................

................................................... ................................ 18 C.1.2 Water Quality ...............................

................................................... ............................. 20
C.2 Seafloor Habitats and Biota ...................

................................................... ............................... 22
C.2.1 Soft Bottom Benthic Communities .............

................................................... ................ 23 C.2.2 High-Density Deepwater Benthic Communities ..

................................................... ....... 25 C.2.3 Designated Topographic Features..............

................................................... ................ 27
C.2.4 Pinnacle Trend Area Live Bottoms ............

................................................... ................. 28
C.2.5 Eastern Gulf Live Bottoms ...................

................................................... ...................... 28 C.3 Threatened, Endangered, and Protected Species a nd Critical Habitat ............................... ....... 28 C.3.1 Sperm Whale (Endangered) ....................

................................................... ................... 30 C.3.2 Florida Manatee (Endangered) ................

................................................... .................. 33 C.3.3 Endangered Mysticete Whales .................

................................................... ................. 34 C.3.4 Non-Endangered Marine Mammals (Protected) ...

................................................... ..... 35 C.3.5 Sea Turtles (Endangered/Threatened) .........

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

................................................... ...................... 41 C.3.7 Whooping Crane (Endangered) .................

................................................... ................. 43

# CONTENTS
(Continued)

Page

Mississippi Canyon Blocks 940, 984, and 985 May 2011 Environmental Impact Analysis for Supplemental EP Page iii 

### C.3.8 Gulf Sturgeon (Threatened) ..................

................................................... ..................... 44 C.3.9 Beach Mice (Endangered) .....................

................................................... ..................... 45
C.4 Coastal and Marine Birds ......................

................................................... ................................ 46 C.4.1 Marine and Pelagic Birds ....................

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

................................................... ................ 49
C.5 Fisheries Resources ...........................

................................................... ................................... 51 C.5.1 Pelagic Communities and Ichthyoplankton .....

................................................... ........... 51
C.5.2 Essential Fish Habitat ......................

................................................... ........................... 53 C.6 Archaeological Resources ......................

................................................... ............................... 56 C.6.1 Shipwreck Sites .............................

................................................... ............................ 56 C.6.2 Prehistoric Archaeological Sites ............

................................................... ..................... 57
C.7 Coastal Habitats and Protected Areas ..........

................................................... ......................... 58
C.8 Socioeconomic and Other Resources .............

................................................... ....................... 60 C.8.1 Recreational and Commercial Fishing .........

................................................... ............... 60 C.8.2 Public Health and Safety ....................

................................................... ........................ 62 C.8.3 Employment and Infrastructure ...............

................................................... .................. 63
C.8.4 Recreation and Tourism ......................

................................................... ...................... 64
C.8.5 Land Use ....................................

................................................... ............................... 65
C.8.6 Other Marine Uses ...........................

................................................... ......................... 66 C.9 Cumulative Impacts ............................

................................................... .................................. 67 C.9.1 Cumulative Impacts to Physical/Chemical Resou rces .............................................. ...... 68 C.9.2 Cumulative Impacts to Biological Resources ..

................................................... ............ 69 C.9.3 Cumulative Impacts to Socioeconomic Resources

.................................................. ....... 71



## D. Environmental Hazards .........................

................................................... ............. 72 D.1 Geologic Hazards ..............................

................................................... .................................... 72
D.2 Severe Weather ................................

................................................... .................................... 72
D.3 Currents and Waves ............................

................................................... ................................. 72



## E. Alternatives ..................................

................................................... ..................... 72

F. Mitigation Measures ...........................

................................................... ............... 73

G. Consultation ..................................

................................................... .................... 74

H. Preparers .....................................

................................................... ...................... 74

I. References ....................................

................................................... ...................... 74Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page iv 

# LIST OF TABLES

Table Page

1 Notices to Lessees and Operators (NTLs) that are referenced in this Environmental

Impact Analysis (EIA) .............................

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

2 Matrix of impact-producing factors and affected e nvironmental resources ....................... 7

3 Conditional probabilities of a spill in the lease area contacting shoreline segments

(From: Ji et al., 2004) ...........................

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

4 Benthic community data from stations near the lea se area and in similar water

depths sampled during the Northern Gulf of Mexico C ontinental Slope Habitats and Benthic Ecology Study (From: Wei, 2006; Rowe an d Kennicutt, 2009) ...................... 23

5 Federally-listed endangered and threatened specie s in the lease area and along

the northern Gulf coast ...........................

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



# LIST OF FIGURES

Figure Page

1 Vicinity map for the lease area .................

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

2 Bathymetric map of the lease area showing propose d well surface locations .................. 17

3 Location of selected environmental features in re lation to the lease area ....................... 42Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page v



# ACRONYMS AND ABBREVIATIONS

ADIOS Automated Data Inquiry for Oil Spills ASI Airborne Support, Inc. BOEMRE Bureau of Ocean Energy Management,

Regulation and Enforcement BPD bbl/day
CCA Clean Caribbean & Americas
CGA Clean Gulf Associates

CH 4 methane
CO carbon monoxide

CO 2 carbon dioxide DP dynamically positioned
EA Environmental Assessment
EEZ Exclusive Economic Zone
EFH Essential Fish Habitat EIA Environmental Impact Analysis EIS Environmental Impact Statement EP Exploration Plan ESA Endangered Species Act FAD fish-attracting device GC Green Canyon GMFMC Gulf of Mexico Fishery Management

Council

H 2 S hydrogen sulfide
HAPC Habitat Area of Particular Concern HSE health, safety, and environment IPF impact-producing factor

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
MMPA Marine Mammal Protection Act MMS Minerals Management Service MSRC Marine Spill Response Corporation MWCC Marine Well Containment Company NAAQS National Ambient Air Quality Standards NEPA National Environmental Policy Act
NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric

Administration

NO x nitrogen oxides NPDES National Pollutant Discharge Elimination

System
NPS National Park Service
NRC National Research Council

NTL Notice to Lessees NWR National Wildlife Refuge OCS Outer Continental Shelf
OCSLA Outer Continental Shelf Lands Act OSAT Operational Science Advisory Team OSRA Oil Spill Risk Analysis OSRL Oil Spill Response Limited OSRP Oil Spill Response Plan PAH polycyclic aromatic hydrocarbon PM particulate matter PSD Prevention of Significant Deterioration ROV remotely operated vehicle SBM synthetic-based mud

SO x sulfur oxides SWSS Sperm Whale Seismic Study
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 AreaMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 1 

# INTRODUCTION

Project Summary

Shell Offshore Inc. (Shell) is submitting a Supplem ental Exploration Plan (EP) for Mississippi Canyon (MC) Blocks 940, 984, and 985. Shell submit ted an Initial EP for wells D, E, F and G in MC 984 and MC 985, which was approved by the Minera ls Management Service (MMS, now Bureau of Ocean Energy Management, Regulation and E nforcement [BOEMRE]) on July 30, 2008 (Plan Control No. N-9220). An Initial EP for well H with a surface location in MC 984 was approved by the MMS on June 12, 2009 (Plan Control No. N-9383) with BHL in MC 940. Shell is now submitting a Supplemental EP that includes eigh t exploration wells in MC 940, 984, and 985, of which one will be a side-track of well H. These wells are D, E, F, G, H-ST, I, J, and K. Thi s Supplemental EP also incorporates the revised blowo ut scenario and worst case discharge (WCD) information as required by Notice to Lessees (NTL) 2010-N06.

The lease area is 67 miles (108 km) from the neares t shoreline, 117 miles (188 km) from the onshore support base at Port Fourchon, Louisiana, a nd 92 miles (148 km) from the helicopter base at Boothville, Louisiana ( Figure 1 ). Water depths at the wellsites range from 1,213 to 1,269 m (3,978 to 4,164 ft).

The Noble Danny Adkins , a dynamically positioned (DP) semisubmersible rig , or a similar rig, will be used for drilling. Drilling of wells is ex pected to commence during the last quarter of 2011. The average time to drill a well will be app roximately 145 days. The side-track well (H-ST) will take about 65 days to be drilled.



## Purpose of the EIA

This Environmental Impact Analysis (EIA) was prepar ed pursuant to the requirements of the Outer Continental Shelf Lands Act (OCSLA), 43 U.S.C . §§ 1331-1356, and BOEMRE regulations, including 30 CFR 250.212(o) and 250.227. The EIA i s a project- and site-specific analysis of Shell’s planned activities under this EP. The EIA also evaluates potential impacts in accordance with NTL 2008-G04 issued by the BOEMRE.

The EIA presents data, analysis, and conclusions to support BOEMRE reviews as required by the National Environmental Policy Act (NEPA) and ot her relevant Federal laws, including the Endangered Species Act (ESA) and Marine Mammal Prot ection Act (MMPA), as the agency considers this Supplemental EP for approval. It al so identifies the mitigation measures Shell will implement in connection with the planned activ ities.

As specified in NTL 2008-G04, an EIA is a project-s pecific analysis that focuses on the impacts of a specific plan. This EIA addresses the impact- producing factors (IPFs), resources, and impacts associated with the activities proposed in this Supplemental EP including drilling of wells. The EIA also incorporates the revised blowo ut scenario and WCD information required by NTL 2010-N06.Mississippi Canyon Blocks 940, 984, and 985May 2011Environmental Impact Analysis for Supplemental EPPage 2Figure 1. Vicinity map for the lease area.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 3 

### The BOEMRE has performed numerous environmental eva luations of oil and gas activities on the Gulf of Mexico Outer Continental Shelf (OCS). Potential impacts were analyzed at a broader level in the Programmatic Environmental Imp act Statement (EIS) for the OCS Oil and Gas Leasing Program (MMS, 2007a) and in recent mult i-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008), as well as the Environmental Assessment (EA) for Gulf of Mexico deepwater operat ions and activities (MMS, 2000) and a Grid EA for the Marco Polo Development in Green Can yon (GC) 608 (Grid 13) (MMS, 2003).

These studies generated critical data and advanced industry’s and BOEMRE’s large body of existing knowledge on the Gulf of Mexico OCS. They analyze everything from potential impacts on the natural environment to the socioecon omic effects of exploration and development activities. They include numerous tech nical studies ranging from the likely trajectory of spilled oil to the effects of underwa ter noise on threatened and endangered species. They inform agency decision-making on lea se offerings, mitigation measures and lease stipulations, operational requirements, and p ermit restrictions. This substantial body of work, which in part forms the basis for the evaluat ion presented here, will allow the BOEMRE and other regulatory agencies to evaluate Shell’s S upplemental EP and ensure that oil and gas exploration and development activities are performe d in an environmentally sound manner, with minimal impacts on the environment. Shell has incorporated these comprehensive environmental analyses by reference and built on th em with project-specific and site-specific analyses.



## OCS Regulatory Framework

The regulatory framework for OCS activities in the Gulf of Mexico has been summarized by MMS (2010). Under the OCSLA, the U.S. Department o f the Interior (USDOI) is responsible for the administration of mineral exploration and devel opment of the OCS. Within the USDOI, the BOEMRE is charged with the responsibility of managi ng and regulating the development of OCS oil and gas resources in accordance with the pr ovisions of the OCSLA. The BOEMRE operating regulations are in 30 CFR Parts 250, 251, and 254.

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

NTLs are formal documents issued by the BOEMRE that provide clarification, description, or interpretation of a regulation or standard; provide guidelines on implementing a special lease stipulation or regional requirement; provide a bett er understanding of the scope and meaning of a regulation by explaining the BOEMRE interpreta tion of a requirement; or transmit administrative information such as current telephon e listings or changes in BOEMRE personnel
or office address. Table 1 lists and summarizes the NTLs that are referenced in this EIA.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 4 

### Table 1. Notices to Lessees and Operators (NTLs) th at are referenced in this Environmental Impact Analysis (EIA).

NTL Title Summary

2010-N10 Statement of Compliance with

Applicable Regulations and
Evaluation of Information Demonstrating Adequate Spill Response and Well Containment

Resources Informs operators using subsea blowout preventers ( BOPs) or surface BOPs on floating facilities that applicatio ns for well permits must include a statement signed by an authorized co mpany official stating that the operator will conduct all activiti es in compliance with all applicable regulations, including the incr eased safety measures regulations (75 FR 63346). Informs operators t hat the BOEMRE will be evaluating whether each operator has submitted adequate information demonstrating that it has acce ss to and can deploy containment resources to promptly respond to a blowout or
other loss of well control.

2010-N06 Information Requirements for

Exploration Plans, Development and Production Plans, and Development Operations Coordination Documents
on the OCS Rescinds the limitations set forth in NTL 2008-G04 regar ding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in blow out scenario and worst case discharge scenario descriptions.

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

- density deepwater benthic communities (including chemosynthetic and d eepwater coral communities) from damage caused by Outer Cont inental Shelf (OCS) oil and gas activities in water depths greate r than 300 m (984 ft). Prescribes separation distances of 610 m (2,000 ft) from each mud and cuttings discharge location and 76 m (250 ft) from all
other seafloor disturbances.

2009-G39 Biologically-Sensitive Underwater

Features and Areas Guidance for avoiding and protecting biologically s ensitive features and areas (i.e., topographic features, pinnacles, l ow-relief live bottom areas, and other potentially sensitive biolo gical features) when conducting OCS operations in water depths less than 300 m (984 ft) in the Gulf of Mexico.

2009-G06 Military Warning and Water Test

Areas Provides contact links to individual command headqu arters for the military warning and water test areas in the Gulf o f Mexico. Lease stipulations require lessees or designated operator s to enter into an agreement with the appropriate individual military command headquarters concerning the control of electromagne tic emissions and use of boats and aircraft in the applicable war ning area or water test area before commencing such traffic.

2008-G04 Information Requirements for

Exploration Plans and Development Operations Coordination Documents Guidance on the information requirements for OCS plans, including EIA requirements and information regarding complian ce with the provisions of the Endangered Species Act and Marine Mammal

Protection Act.

2007-G04 Vessel Strike Avoidance and

Injured/Dead Protected Species Reporting R ecommends protected species identification training

, recommends that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop thei r vessel to avoid striking protected species, and requires oper ators to report sightings of any injured or dead protected species.

2007-G03 Marine Trash and Debris Awareness

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

2005-G07 Archaeological Resource Surveys

and Reports Provides guidance on regulations regarding archaeol ogical discoveries, specifies requirements for archaeologi cal resource surveys and reports, and outlines options for prote cting archaeological resources.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 5 

## Oil Spill Prevention and Contingency Planning

Shell submitted a Gulf of Mexico Regional Oil Spill Response Plan (OSRP) to the BOEMRE as a fundamental component of the planned drilling progr am on October 26, 2010. The OSRP certifies that Shell has the capability to respond to the maximum extent practicable to a WCD (30 CFR 254.2). The OSRP demonstrates Shell’s capa bilities to rapidly and effectively manage oil spills that may result from drilling operations . Despite the extremely low likelihood of a large oil spill event occurring during the project, Shell has designed its response program based upon a regional capability of responding to a range of spill volumes that increase from small operational spills up to and including a WCD from a well blowout. Shell’s program meets the response planning requirements of the relevant coas tal states and Federal oil spill planning regulations. The OSRP includes information regardi ng Shell’s regional oil spill organization and dedicated response assets, potential spill risks, a nd local environmental sensitivities. The OSRP presents specific information on the response progr am that includes a description of personnel and equipment mobilization, the incident management team organization, and the strategies and tactics used to implement effective and sustained spill containment and recovery operations.



## EIA Organization

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

Section C (Impact Analysis).Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 6



# A. IMPACT-PRODUCING FACTORS

Table 2 is a matrix of IPFs and potentially affected envir onmental resources adapted from
Form MMS-142. An “X” indicates that an IPF could r easonably be expected to affect a certain resource, and a dash (--) indicates no impact or ne gligible impact. Where there may be an effect, an analysis is provided in Section C . Potential IPFs for the proposed activity are lis ted below and briefly discussed in the following subsec tions:

• Drilling rig presence (including noise and lights);

• Physical disturbance to the seafloor;

• Air pollutant emissions;

• Effluent discharges;

• Water intake;

• Onshore waste disposal;

• Marine debris;

• Support vessel and helicopter traffic; and

• Accidents.



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

The wells will be drilled using the Noble Danny Adkins or a similar DP semisubmersible. The rig will be on site for an estimated 145 days per well. Four offshore support vessels will be used during the drilling program and at least one of the se will always be in the vicinity of the drilling rig to provide assistance as necessary. The physic al presence of a drilling rig in the ocean can attract pelagic fishes and other marine life, as di scussed in Section C.5.1 . A semisubmersible maintains buoyancy using ballasted, watertight pont oons located below the sea surface. The operating deck is located above the tops of passing waves. Structural columns connect the pontoons and operating deck. When the rig moves it s location, the pontoons are de-ballasted so that the rig can float on the sea surface. The Noble Danny Adkins uses thrusters to hold or adjust its position.

Drilling operations produce noise that includes str ong tonal components at low frequencies, including infrasonic frequencies in at least some c ases (MMS, 2000). Drilling noise from semisubmersibles is not particularly intense and is strongest at low frequencies, averaging 10 to 500 Hz (Richardson et al., 1995). From a sem isubmersible, sound and vibration are transmitted to the water either through the air or the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and avi ation safety in accordance with Federal regulations.



## A.2 Physical Disturbance to the Seafloor

Semisubmersibles like the Noble Danny Adkins do not use anchors for holding or stabilization during drilling operations. There will be minimal disturbance to the seafloor and soft bottom communities during positioning of the wellbore and BOP. Physical disturbance of the seafloor will be limited to the area where the wellbore pene trates the substrate, where mud and drill cuttings will be deposited.Mississippi Canyon Blocks 940, 984, and 985May 2011Environmental Impact Analysis for Supplemental EPPage 7Table 2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (--) = no impact or negligible impact.Environmental ResourcesImpact-producing FactorsDrilling RigPresence (incl.noise & lights)PhysicalDisturbanceto SeafloorAirPollutantEmissionsEffluentDischargesWaterIntakeOnshoreWasteDisposalMarineDebrisSupportVessel/HeloTrafficAccidentsSmall FuelSpillOil Spill(WCD)Physical/Chemical EnvironmentAir quality and greenhouse gases----X----------X(6)X(6)Water quality------X--------X(6)X(6)Seafloor Habitats and BiotaSoft bottom benthic communities------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 Gulflive bottoms----(3)----(3)------------Threatened, Endangered, and Protected Species and Critical HabitatSperm 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------------XX(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 BirdsMarine and pelagic birdsX------------XX(6)X(6)Shorebirds and coastal nesting birds--------------X--X(6)Fisheries ResourcesPelagic communities and ichthyoplanktonX----XX------X(6)X(6)Essential Fish HabitatX----XX------X(6)X(6)ArchaeologicalResourcesShipwreck sites----(7)--------------X(6)Prehistoric archaeological sites----(7)--------------X(6)Coastal Habitats and Protected AreasBeaches------------------X(6)Wetlands and seagrass beds--------------X--X(6)Coastal wildlife refugesandwilderness areas------------------X(6)Socioeconomic and Other ResourcesRecreational and commercial fishingX--------------X(6)X(6)Public health and safety------------------X(6)Employment and infrastructure------------------X(6)Recreation and tourism------------------X(6)Land use------------------X(6)Other marine uses------------------X(6)WCD = worst case discharge.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 8 

### Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary o r topographic feature. Specifically, if the well, platform site, or any anchors will be on the seafloor within the foll owing: (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 Topograph ic Features Stipulation attached to an Outer Continent al 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 prot ected by the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near an y marine sanctuary, topographic feature, or no-activity zone. There are no submarine banks in the blocks.
(2) Activities with any bottom disturbance within a n 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 wh ere seafloor habitats are protected by the Live Bot tom (Low-Relief) Stipulation attached to an OCS lease.

• The Live Bottom (Low-Relief) Stipulation is not app licable to the lease area.
(4) Activities on blocks designated by the BOEMRE a s being in water depths 300 m or greater.

• No impacts on high-density deepwater benthic commun ities are anticipated. There are no features indicative of high-density chemosynthetic communiti es or coral communities within 610 m (2,000 ft) of any drilling mud/cuttings discharge location. Beca use a semisubmersible will be used, there will be n o seafloor disturbances due to anchoring.
(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be enco untered.

• Based on CFR 250.417(c), Shell is requesting that t he BOEMRE classify the area as “H 2 S absent.”

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

• Accidental hydrocarbon spills could affect the reso urces marked (X) in the matrix, and impacts are analyzed in Section C

. (7) All activities that involve seafloor disturbanc es, including anchor emplacements, in any OCS block designated by the BOEMRE as having high-probability for the oc currence of shipwrecks or prehistoric sites, includ ing such blocks that will be affected that are adjacent to t he lease block in which your planned activity will occur. If the proposed activities are located a sufficient distan ce from a shipwreck or prehistoric site that no imp act would occur, the EIA can note that in a sentence or two.

• No impacts on archaeological resources are expected . The lease area is on the list of high-probabilit y blocks for shipwrecks. The archaeological survey d etected 106 unidentified sidescan sonar targets, several drag scars, and geological features within the survey area, of which 23 were in MC 940, 984, a nd
985. There were no sonar contacts with acoustic si gnature that require archaeological avoidance or further investigation. The lease is well beyond the 60-m depth contour used by the BOEMRE as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because a dynamic ally positioned semisubmersible will be used, there will be no seafloor disturbances due to anchoring.
(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals
or sea turtles or their critical habitats.

• IPFs that may affect marine mammals, sea turtles, o r their critical habitats include drilling rig pres ence and emissions, support vessel and helicopter traffi c, and accidents. See Section C

. (9) Production activities that involve transportati on of produced fluids to shore using shuttle tanker s or barges.



### • Not applicable.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 9 

## A.3 Air Pollutant Emissions

Air pollutant emissions are estimated in Supplemental EP Section 8 . Offshore air pollutant emissions will result from operations of the drilli ng rig, as well as service vessels and helicopters. These emissions occur mainly from com bustion of diesel fuel. The combustion of fuels occurs on diesel-powered generators, pumps, o r motors and from lighter fuel motors. Primary air pollutants typically associated with OC S activities are suspended particulate matter (PM), sulfur oxides (SO
x 

### ), nitrogen oxides (NO
x 

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

The Air Quality Emissions Report prepared in accord ance with the BOEMRE requirements shows that the projected emissions for the drilling rig are below exemption levels; therefore, according to 30 CFR 250.303, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. N o further analysis or control measures are required. However, Shell will use low sulfur fuel (0.05% by weight) to further reduce any possible impacts.



## A.4 Effluent Discharges

Effluent discharges are summarized in Supplemental EP Section 7 . All offshore discharges will
be in accordance with the National Pollutant Discha rge Elimination System (NPDES) General Permit No. GMG290000 issued by the USEPA. Discharg es will be in compliance with and monitored as required by the permit.

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

A synthetic-based mud (SBM) system will be used aft er the riser is installed. The SBM will not be discharged but will be recovered and transported to the shorebase for recycling by the mud company. SBM cuttings will be discharged overboard via a downpipe to 515 ft below the water surface, after treatment with a cuttings drye r, which is expected to reduce retention of the SBM fluid on cuttings to well below the NPDES p ermit requirement of 6.9%. The estimated volume of cleaned SBM drill cuttings to be discharg ed is 6,500 barrels (bbl)/well.

Other effluent discharges in accordance with the NP DES permit will include excess cement, non-contact cooling water, treated sanitary and dom estic wastes, deck drainage, desalination unit brine, uncontaminated fire water and ballast w ater.



## A.5 Water Intake

Seawater will be drawn from the ocean for once-thro ugh, non-contact cooling of machinery on the drilling rig. The estimated intake and dischar ge of cooling water is 130,600 bbl/day (BPD) (5.48 million gallons per day [MGD]). The rig will also use another 130,600 BPD (5.48 MGD) for
fire water.

Section 316(b) of the Clean Water Act requires NPDE S permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmen tal impact from impingement andMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 10 

### entrainment of aquatic organisms. Construction of the rig planned for use in this Supplemental EP, the Noble Danny Atkins , started prior to July 17, 2006, and therefore is not subject to the cooling water intake permit requirem ents of NPDES Permit GMG 290000. If a similar type rig is selected, it will comply with a ll applicable NPDES requirements.



## A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in Supplemental EP Section 7 . Waste volume is estimated to be approximately 7,000 bbl/well. Expl oration and Production (E&P) waste will be collected and disposed of at Newpark Environmental Services or US Liquids of Louisiana (Fourchon, Louisiana). Non-hazardous trash and deb ris and non-recyclable waste will be transported to the Republic/BFI landfill in Sorrent o, Louisiana, or the parish landfill in Avondale, Louisiana. Additionally, non-hazardous r ecyclable waste will be recycled at Omega Waste Management, Patterson, Louisiana, or at ARC o f New Iberia, New Iberia, Louisiana, via the Recycle the Gulf Program. Hazardous waste such as paints, solvents, and unused chemicals will be disposed of at Safety Kleen Syste ms, Inc., Denton, Texas, while used oil will be sent to Omega Waste Management for recycling, an d glycol will be sent to Safety Kleen Systems, Inc. for recycling. Universal waste inclu ding batteries, lamps, glass, and mercury-contaminated waste will be recycled at Lamp Environmental Industries, Hammond, Louisiana. Oil filters, oily rags and pads, empty drums, and cooking oil will be sent to Omega Waste Management, Patterson, Louisiana for recyclin g. At the onshore facilities, wastes will be recycled or disposed of according to all applica ble regulations.



## A.7 Marine Debris

Trash and debris released into the marine environme nt can harm marine mammals, turtles, and birds through entanglement and ingestion. Shel l will adhere to the International
Convention for the Prevention of Pollution from Shi ps (MARPOL 73/78) Annex V requirements, USEPA and USCG regulations, and BOEMRE regulations and NTLs regarding solid wastes. The BOEMRE regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (e.g., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools and containers (especially drums), and other material. USCG and USEPA regulations require operators to become proactive in avoiding a ccidental loss of solid waste items by developing waste management plans, posting informat ional placards, manifesting trash sent to shore, and using special precautions such as cov ering outside trash bins to prevent accidental loss of solid waste. Shell complies wit h NTL 2007-G03, which instructs operators to exercise caution in the handling and disposal of sm all items and packaging materials, requires the posting of placards at prominent locations on o ffshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process. Shell’s compliance with all applicable laws, regula tions, and NTL 2007-G03 will avoid significant impacts on the environment.



## A.8 Support Vessel and Helicopter Traffic

Shell will use existing shorebased facilities at Po rt Fourchon and Boothville, Louisiana, for onshore support for water and air transportation, r espectively. No terminal expansion or construction is planned at either location.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 11 

### The supply base at Port Fourchon is operated by She ll and located on Bayou LaFourche, approximately 3 miles (5 km) from the Gulf of Mexic o. During drilling, the project will be supported by two crew boats and four offshore suppo rt vessels; crew boats will make two round-trips per week between the drilling facility and the onshore supply base, while at least one support vessel will be in the field at all time s. The boats will normally move to the project
area via the most direct route from the shorebase.

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



## A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential a ccidents:

• A small fuel spill, which is the most likely type o f spill during OCS development activities;
and

• An oil spill resulting from an uncontrolled blowout . A blowout resulting in a WCD is an extremely rare event, and the probability of such a n event will be minimized by Shell’s well control and blowout prevention measures as detailed in Supplemental EP Section 2j . In accordance with NTL 2010-N06, the estimated rate is 314,000 bbl for the first day with a 30-day average of 280,000 BPD. The estimated time to drill a relief well is 185 days, and the total volume of a spill over this duration woul d be 48 million barrels of oil (MMBO).

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

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

.


### A.9.2 Small Fuel Spill

Spill Size . According to the analysis in MMS (2007b), the mo st likely type of small spill (<1,000 bbl) as a result of OCS activities is a min or diesel fuel spill. Historically, most diesel spills have been < 1 bbl, and this size is predicted to be the most co mmon in ongoing and
future OCS activities in the Western and Central Gu lf of Mexico Planning Areas (MMS, 2007b). The average size for spills < 1 bbl is 0.07 bbl, and the median size for spills o f 1 to 10 bbl is 3 bbl (MMS, 2007b). For this analysis, a small diesel fu el spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of s uch a spill would be a hose rupture resulting
in the loss of the contents of a fuel transfer hose , which is less than 3 bbl.

Spill Fate . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as th e effectiveness of spill response activities.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 12 

### However, given the open ocean location of the lease area, the duration of a small spill and the opportunity for impacts to occur would be very brie f.

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council [NRC], 2003). The constituents of these oils are l ight to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidat ion. Diesel is so light that it will not sink to the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with hi gh suspended solids loads (NRC, 2003) and would not be expected to occur to any appreciable d egree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degra ded by naturally occurring microbes (NOAA, 2006).

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

The ADIOS2 results, coupled with spill trajectory i nformation discussed below for a large spill, indicate that a small fuel spill would not have any impacts on coastal or shoreline resources. The lease area is 67 miles (108 km) from the neares t shoreline (Louisiana). Modeling results discussed below indicate that a spill in the lease area would have a 4% probability of contacting the nearest Louisiana shoreline (Plaquem ines Parish) within 10 days after a spill. By this time, essentially 100% of a small fuel spill w ould have been dispersed or evaporated by natural processes, even if no response measures wer e implemented. MMS (2007b) similarly concluded that spills <1,000 bbl are not expected t o persist as a slick on the surface of the water beyond a few days and are unlikely to make la ndfall or reach coastal waters prior to breaking up. MMS (2007b) noted that this conclusio n is supported by a previous analysis of 3-day trajectory model runs, previous weathering an alyses, and historical records of spill
incidents.

Spill Response . In the unlikely event the shipboard prevention p rocedures fail to prevent a fuel spill, response equipment and trained personne l would be available to ensure that any spill effects are localized and would result only i n short-term environmental consequences. Supplemental EP Section 9b provides a detailed discussion of Shell’s response to a spill.



### A.9.3 Crude Oil Spill (Worst Case Discharge)

A blowout resulting in a large oil spill is an extr emely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures detailed in Supplemental EP Section 2j . Blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis u sing the SINTEF database estimates a blowout frequency of 0.0017 per development well fo r non-North Sea locations (International Association of Oil & Gas Producers, 2010). As note d by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 13 

### The risk of a blowout during this project is signif icantly lower than indicated by these statistics because the well design and drilling program were d eveloped using information gathered during the drilling of the previous well (H) in MC 940. During drilling of the previous well, the reservoirs were fully logged and evaluated. Substa ntial data associated with the reservoirs were gathered including core, pressure, and fluid d ata. Data gained during these earlier operations provide substantial information that was used in preparing for the proposed operation.

Spill Size . In accordance with requirements of NTL 2010-N06, Shell has estimated a WCD for this Supplemental EP as 314,000 BPD for the first d ay with a 30-day average of 280,000 BPD.
The estimated time to drill a relief well is 185 da ys, and the total volume of a spill over this duration would be 48 MMBO. The detailed analysis o f this calculation can be found in Supplemental EP Section 2j

.
Shell has a robust system in place to prevent blowo uts. Included in Supplemental EP Sections 2j and 9b is Shell’s response to NTL 2010-N06, which include s descriptions of measures to prevent a blowout, reduce the likelihoo d of a blowout, and conduct effective and early intervention in the event of a blowout. Shel l will also comply with NTL 2010-N10 and the Interim Final Drilling Safety Rule, which specify a dditional safety measures for OCS activities.

Spill Trajectory . The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that use s realistic data for winds and currents to predict spill fate. The OSRA report by Ji et al. ( 2004) provides conditional contact probabilities for shoreline segments. The results for Launch Are a 58 (where the lease area is located) are presented in Table 3 . The model predicts no shoreline contact within 3 days. After 10 days, three Louisiana parishes may be contacted. After 3 0 days, 11 counties and parishes from Texas to the Florida Panhandle may be contacted. P laquemines Parish, Louisiana, has the greatest probability of shoreline contact, with a 4 % and 8% chance within 10 and 30 days, respectively.

Table 3. Conditional probabilities of a spill in th e lease area contacting shoreline segments (From: Ji et al., 2004). Values are conditional pr obabilities that a hypothetical spill in the lease area (represented by OSRA Launch Area 58) could contact shoreline segments within 3, 10, or 30 days.

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

C10 Galveston , Texas

-- -- 1

C12 Jefferson , Texas

-- -- 1
C13 Cameron , Louisiana

-- -- 3

C14 Vermili on, Louisiana

-- -- 2

C15 Iberia , Louisiana

-- -- 1

C17 Terrebonne , Louisiana

-- 1 3

C18 Lafourche , Louisiana

-- 2 3

C19 Jefferson , Louisiana

-- -- 1

C20 Plaquemines , Louisiana

-- 4 8

C21 St. Bernard, Louisiana

-- -- 1

C28 Okaloosa , Florida

-- -- 1

a Conditional probability refers to the probability of contact within the stated time period, assuming that a spill has occurred (-- indicates less than 0.5%).Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 14 

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

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

Weathering decreases the concentration of oil and p roduces changes in its chemical composition, physical properties, and toxicity. Th e more toxic, light aromatic and aliphatic hydrocarbons are lost rapidly by evaporation and di ssolution from the slick on the water surface. Evaporated hydrocarbons are degraded rapi dly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n-alkanes and then the light aromatics from the oil. Other petro leum components are biodegraded more slowly. Photooxidation attacks mainly the medium a nd high molecular weight PAHs in the oil
on the water surface.

Spill Response . Shell is a founding member of the Marine Well Co ntainment Company (MWCC) and has access to an integrated subsea well control and containment system that can be rapidly deployed through the MWCC. The MWCC is a non-profit organization that manages and provides fully trained crews and operates the s ubsea containment system during a response. The near-term containment response capab ility will be specifically addressed in Shell’s NTL 2010-N10 submission at the time an Appl ication to Drill (APD) is submitted and will include equipment and services available to Shell t hrough MWCC’s development of near-term capability and other industry sources. Shell is a member of Clean Caribbean & Americas (CCA), Marine Spill Response Corporation (MSRC), Clean Gul f Associates (CGA), and Oil Spill Response Limited (OSRL), organizations that are committed to providing the resources necessary to respond to a spill as outlined in Shell’s OSRP (Oct ober 2010).

The experience of gaining control over the Macondo well has resulted in a better understanding of the necessary equipment and system s for well containment. As a result, industry and government are better equipped and pre pared today to contain an oil well blowout in deepwater (see page 17 of the Decision M emorandum dated October 1, 2010 [Bromwich, 2010]). Shell is further analyzing thes e advances and incorporating them into a comprehensive approach to help prevent and, if need ed, control another deepwater control incident. Shell is also investing in research and development to improve containment systems.

The primary offshore response would involve mechani cal recovery. The primary response equipment that would be mobilized to the spill loca tion for spills in normal and adverse
weather conditions is included in the Offshore On-W ater Recovery Activation List in the OSRP.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 15 

### Chemical dispersion capabilities are also readily a vailable from resources such as MSRC at Stennis, Mississippi, and Coolidge, Arizona; CGA/Ai rborne Support, Inc. (ASI) in Houma, Louisiana; Oil Spill Response in South Hampton, UK and Singapore; and CCA in Ft. Lauderdale, Florida. Available equipment for surface and subse a application of dispersants, response times, and support resources are identified in the OSRP.

Open-water in-situ burning (ISB) may also be used as a response strat egy, depending on the circumstances of the release. If appropriate condi tions exist and approval from the Unified Command is received, one or multiple ISB task force s could be deployed offshore.

See Supplemental EP Sections 2j and 9b for a detailed description of Shell’s site-specifi c response to the worst case spill for this plan. Th ese sections, along with Shell’s OSRP, also include a description of surface and subsea contain ment capabilities that could be implemented in the event of the worst case spill at this site.



### A.9.4 Other Accidents Not Analyzed in Detail

The lease sale EIS (MMS, 2007b) discusses three oth er types of accidents: chemical spills, vessel collisions, and loss of well control. These accidents are discussed briefly below. No hydrogen sulfide (H 2 

### S) is expected at this site, and no other site-spec ific issues have been identified for this Supplemental EP. The analysis in the lease sale EIS for these topics is incorporated by reference.

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

A study of environmental risks of chemical products used in OCS activities determined that only two chemicals could potentially affect the mar ine environment: zinc bromide and ammonium chloride (Boehm et al., 2001). The risk o f a spill for these chemicals is very low.
Most other chemicals are either nontoxic or used in small quantities. No significant impacts are expected from chemical spills.

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

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well
control is a broad term that includes minor to seri ous well control incidents, while blowoutsMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 16 

### are considered to be a subset of more serious incid ents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well control may resu lt in the release of synthetic drilling fluid or loss of oil. Shell has a robust system in place to prevent loss of well control. Included in this Supplemental EP is Shell’s response to NTL 2010-N06 , which includes descriptions of measures to prevent a blowout, reduce the likelihood of a bl owout, and conduct effective and early
intervention in the event of a blowout. Shell will also comply with NTL 2010-N10 and the Interim Final Drilling Safety Rule, which specify a dditional safety measures for OCS activities.

See Supplemental EP Sections 2j and 9b for further information.

H 2 

### S Release . Based on CFR 250.417(c), Shell requests that the Regional Supervisor, Field Operations, classify the area in the proposed drill ing operations as an area where the absence
of H 2 

### S has been confirmed.



# B. AFFECTED ENVIRONMENT

The lease area is in the north-central Gulf of Mexi co, 67 miles (108 km) from the nearest shoreline, 117 miles (188 km) from the onshore supp ort base at Port Fourchon, Louisiana, and 92 miles (148 km) from the helicopter base at Booth ville, Louisiana ( Figure 1 ).

The seafloor gradient in the MC 940, 984, and 985 s tudy area ranges from near flat to approximately 15.4 o 

### . The average slope is 1.77 o 

### indicating the study area in general is flat. The greatest seafloor gradients occur along seafloor fa ult escarpments. The seabed morphology in this portion of the slope consists of a series of r idges and valleys, the axes of which trend approximately northwest-southeast parallel to the a xis of the Mississippi Canyon and perpendicular to the regional bathymetric contours (GEMS, 2007). The wellsites are in areas of the seafloor that slope gently southeast, east-s outheast or southwest at angles between

1.3 o 

### and 2.5 o 

### on a relatively featureless ramp, with water depth s ranging from 1,213 to 1,269 m (3,978 to 4,164 ft) ( Figure 2 ). The sidescan sonar survey confirmed the presenc e of
one subsea well in the lease area and the absence o f other man-made infrastructure, including pipelines.

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

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

The lease area is approximately 68 miles (110 km) s outhwest of the Macondo spill site. Based on an analysis of satellite imagery (ESRI, 2010), t he surface slick extended over the lease areaMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 17 

### at various times prior to capping of the well; ther efore, existing water quality in the lease area could have been temporarily affected. Macondo spil l impacts are addressed in Section C.9 (Cumulative Impacts) where available and applicable

.

Figure 2. Bathymetric map of the lease area showing proposed well surface locations. Well H was

drilled previously and will be side-tracked; the ot hers are new wells to be drilled.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 18 

# C. IMPACT ANALYSIS

This section analyses the potential direct and indi rect impacts of routine activities and accidents. Cumulative impacts are discussed in Section C.9

.
Impacts have been analyzed extensively in recent mu lti-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008) as well as the EA for Gulf of Mexico deepwater operations and activities (MMS, 20 00) and a Grid EA for the Marco Polo Development in GC 608 (MMS, 2003). Site-specific i ssues are addressed in this section as appropriate.


## C.1 Physical/Chemical Environment

C.1.1 Air Quality

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

As of April 2011, all Louisiana, Mississippi, Alaba ma, and Florida coastal counties and parishes are in attainment of the National Ambient Air Quali ty Standards (NAAQS) for all criteria pollutants (USEPA, 2011). Two metropolitan areas i n Texas are nonattainment areas for 8-h ozone (Dallas-Fort Worth, and Houston-Brazoria), an d El Paso County is a nonattainment area
for PM 10 

### (USEPA, 2011).

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

IPFs potentially affecting air quality are air poll utant emissions and two types of accidents: a small fuel spill and a large oil spill (WCD).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF li kely to affect air quality. Offshore air pollutant emissions will result from the operation of the drilling rig as well as helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel-powe red generators, pumps, or motors and from lighter fuel motors. Primary air pollutants t ypically associated with OCS activities are suspended PM, SO
x 

### , NO
x 

### , VOCs, and CO.

Due to the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central Gulf of Mexico Planning Area are projec ted to have minimal impacts to onshore airMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 19 

### quality because of the prevailing atmospheric condi tions, emission heights, emission rates, and
the distance of these emissions from the coastline. The Air Quality Emissions Report (see Supplemental EP Section 8 ) prepared in accordance with BOEMRE requirements s hows that the projected emissions for PM, SO
x 

### , NO x 

### , VOCs, and CO are below exemption levels; therefore, according to 30 CFR 250.303, the emissio ns will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required. However, Shell will use low -sulfur fuel (0.05% by weight) to further reduce any possible impacts.

The Breton Wilderness Area, which is part of the Br eton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air quality area. The BOEMRE is required to notify the National Park Service (NPS) and the USFWS if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sources wit hin 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upo n by the administering agencies (NPS, 2010). The lease area is approximately 99 mi les (159 km) from the Breton Wilderness Area. Shell does not anticipate any impact on the Class I area but will comply with any emissions requirements as directed by the BOEMRE.



### Impacts of a Small Fuel Spill

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

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

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



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

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

A large oil spill (WCD) would affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts w ould depend on the meteorological and oceanographic conditions at the time and the effect iveness of spill response measures. Additional air quality impacts could occur if respo nse measures included ISB of the floating oil. Burning would generate a plume of black smoke and r esult in emissions of NO x 

### , SO x 

### , CO, and PM, as well as greenhouse gases.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 20 

### Due to the lease area location (67 miles [108 km] f rom the nearest shoreline), most air quality impacts would occur in offshore waters. Depending on the spill trajectory and the effectiveness of spill response measures, coastal a ir quality could also be affected. Based on the OSRA modeling predictions ( Table 3 ), Plaquemines Parish, Louisiana, is the coastal ar ea most likely to be affected.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on air quality are expected.



### C.1.2 Water Quality

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

The lease area is approximately 68 miles (110 km) s outhwest of the Macondo spill site. Based on satellite imagery (ESRI, 2010), the surface slic k extended over the lease area during the spill, and therefore existing water quality in the lease area could have been temporarily affected. The Operational Science Advisory Team (O SAT, 2010) reported that after August 2010, waters and sediments in the deepwater Gulf of Mexico beyond 1.8 miles (3 km) from the
Macondo wellsite were below USEPA acute and chronic benchmarks for PAHs and were not hypoxic. These observations indicate that baseline environmental conditions in the lease area are unlikely to have been significantly altered by the spill.

IPFs potentially affecting water quality are efflue nt discharges and two types of accidents: a small fuel spill and a large oil spill (WCD).



### Impacts of Effluent Discharges

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

Treated sanitary and domestic wastes may have a sli ght transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements will be met and little or no impact on water quality is ant icipated.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 21 

### Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work ar eas. Rainwater that falls on uncontaminated areas of the drilling rig will flow overboard witho ut treatment. However, rainwater that falls on the drilling rig deck and other areas such as ch emical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements. Little or no impact on water quality is anticipated.

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

Support vessels will discharge treated sanitary and domestic wastes. These will have a slight effect on water quality in the immediate vicinity o f the discharges. All support vessel discharges will be in accordance with USCG regulati ons and, as applicable, the NPDES Vessel General Permit, and therefore are not expected to c ause significant impacts on water quality.



### Impacts of a Small Fuel Spill

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

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and th eir degradation products. The extent and persistence of impacts would depend on the mete orological and oceanographic conditions at the time and the effectiveness of spill response measures. However, it is estimated that more than 90% of a small diesel spill would be evap orated or dispersed within 24 hours (see
Section A.9.2 ). The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather c onditions.

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

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



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

Potential impacts of a large oil spill on water qua lity are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b, 2008). A large spill would affect waterMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 22 

### quality by producing a slick on the water surface a nd increasing the concentrations of petroleum hydrocarbons and their degradation produc ts. The extent and persistence of impacts would depend on the meteorological and ocea nographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the surface, although new information from the M acondo spill indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint An alysis Group, 2010a,b,c). A report by Kujawinski et al. (2011) indicates that chemical co mponents of subsea dispersants used during the Macondo spill persisted for up to two months an d were detectable up to 186 miles (300 km) from the wellsite at a water depth of 1,00 0 to 1,200 m (3,280 to 3,937 ft).

Once oil enters the ocean, a variety of physical, c hemical, and biological processes acts to disperse the oil slick. These processes include sp reading, evaporation of the more volatile constituents, dissolution into the water column, em ulsification of small droplets, agglomeration sinking, microbial modification, phot ochemical modification, and biological ingestion and excretion (NRC, 2003). Marine water quality would be temporarily affected by the dissolved components and small oil droplets tha t do not rise to the surface or are mixed down by surface turbulence. Dispersion by currents and microbial degradation removes the
oil from the water column or dilutes the constituen ts to background levels.

A large oil spill could result in a release of gase ous hydrocarbons that could affect water quality. During the Macondo spill, large volumes o f methane (CH 4 

### ) were released, causing localized oxygen depletion as methanotrophic bacter ia rapidly metabolized the hydrocarbons (Joye et al., 2011; Kessler et al., 2011). However , a broader study of the deepwater Gulf of Mexico found that although some stations had slight ly depressed dissolved oxygen concentrations relative to climatological backgroun d values, concentrations were not low enough to indicate hypoxia (<2.0 mg/L) (OSAT, 2010) . Stations revisited around the Macondo wellhead in October 2010 showed no measurable oxyge n depression (OSAT, 2010).

Due to the lease area location (67 miles [108 km] f rom the nearest shoreline), most water quality impacts would occur in offshore waters. De pending on the spill trajectory and the effectiveness of spill response measures, coastal w ater quality could be affected. Based on the OSRA modeling predictions ( Table 3 ), nearshore waters and embayments of Plaquemines Parish, Louisiana, are the most likely coastal area s where water quality could be affected.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on water quality are expected.



## C.2 Seafloor Habitats and Biota

Water depths at the proposed well surface locations range from 1,213 to 1,269 m (3,978 to 4,164 ft). The seafloor is expected to c onsist mainly of soft bottom. The chemosynthetic community assessment based on the ha zards report by GEMS (2007) did not identify any features that could support high-densi ty deepwater benthic communities within 610 m (2,000 ft) of the wellsites. See Supplemental EP Section 6a for further information.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### According to the BOEMRE (2011), existing informatio n for the deepwater Gulf of Mexico indicates that the seafloor is composed primarily o f soft sediments; hard bottom communities are rare. MC 940, 984, and 985 are within deepwate r Grid 13, and the BOEMRE website indicates that ROV coverage of the seafloor in this grid is adequate to characterize the area (BOEMRE, 2011).



### C.2.1 Soft Bottom Benthic Communities

Data from the recent Northern Gulf of Mexico Contin ental Slope Habitats and Benthic Ecology study (Wei, 2006; Rowe and Kennicutt, 2009) can be used to describe typical benthic
communities in the area. Table 4 summarizes data from two nearby stations in simila r water depths. Sediments at these two stations were predo minantly clay (46% to 54%) and silt (43% to 45%).

Table 4. Benthic community data from stations near the lease area and in similar water depths sampled during the Northern Gulf of Mexico C ontinental Slope Habitats and Benthic Ecology Study (From: Wei, 2006; Rowe and Ke nnicutt, 2009).

Station Location

Relative to

Lease Area Water Depth

(m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna

(individuals/m 2 ) Megafauna

(individuals/ha)
MT-3 15 mi NNE 987 885,995 4,924 1,034

MT-4 21 mi SE 1,401 246,058 3,262 1,548

Meiofaunal and megafaunal abundance from Rowe and K ennicutt (2009); macroinfaunal abundance from Wei (2006).



### Meiofauna (animals passing through a 0.5-mm sieve b ut retained on a 0.062-mm sieve) densities in water depths representative of the lea se area typically range from about 250,000 to 650,000 individuals/m 2 

### (Rowe and Kennicutt, 2009). Nematodes, nauplii, a nd harpacticoid copepods were the three dominant group s in the meiofauna, accounting for
about 90% of total abundance.

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which are a reflection of the meager primar y production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease exponential ly with water depth. Based on an equation presented by Wei (2006), macroinfaunal densities in the water depths of the wellsites are expected to be about 2,621 to 2,733 individuals/m 2 

### , lower than the values in Table 4

.
Polychaetes are typically the most abundant macroin faunal group on the northern Gulf of Mexico continental slope, followed by amphipods, ta naids, bivalves, and isopods. Wei (2006) recognized four depth-dependent faunal zones (1 thr ough 4), two of which are divided horizontally. The lease area is in Zone 2E, which consists of stations on the mid Texas-Louisiana Slope ranging in depth from 625 to 1,828 m (2,050 to 5,997 ft). The five most abundant species in Zone 2E were the polychaetes Litocorsa antennata

, Aricidea suecica

, Tharyx marioni , and Paralacydonia paradoxa and the bivalve Heterodonta sp.

Megafaunal density from nearby stations MT-3 and MT -4 was 1,034 and 1,548 individuals/ha, respectively ( Table 4 ). Densities of 300 to 2,000 individuals/ha were r eported from other stations in a similar depth range. Common megafaun a included motile groups such asMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 24 

### decapods, ophiuroids, holothurians, and demersal fi shes, as well as sessile groups such as sponges and anemones.

Bacteria are also an important component in terms o f biomass and cycling of organic carbon (Cruz-Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about 1 to 2 grams of carbon per square meter (g C/m 2 

### ) in the top 15 cm of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting benthic communities are effluent discharges (drilling muds and cuttings) and a large oil spill (WCD) resulting fro m a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on
the sea surface. There will be no disturbance to s oft bottom communities on the seafloor during positioning of the DP semisubmersible Noble Danny Adkins

.


### Impacts of Effluent Discharges

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

Discharges of treated SBM cuttings from the rig may affect benthic communities, primarily
within several hundred meters of the wellsites. Th e fate and effects of SBM cuttings have been reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico by Continental Shelf Associates, Inc. (20 04, 2006). In general, cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated organic ca rbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate and concentrations exceed approximately 1,000 mg/kg, benthic infaunal communities may be adversely affected due to both the toxicity of the base fluid and orga nic enrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 

### S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic fluid is decomposed b y microbes, the area will gradually return to pre-drilling conditions. Disturbed sediments will be recolonized through larval settlement and migration from adjacent areas.

The areal extent of impacts from drilling discharge s will be small. Assuming a typical effect radius of 500 m (1,640 ft), the affected area aroun d each wellsite would represent about 3% of the seafloor within a lease block. For the eight s urface locations in this exploration drilling program, the total impact area would be 628 ha (1,5 52 ac). Soft bottom communities are ubiquitous along the northern Gulf of Mexico contin ental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic c ommunities on a regional basis. ThisMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 25 

### conclusion is in accord with the findings of the EA for Grid 13 prepared by MMS (2003), which concluded that development activities in this area would have minimal impacts on the ecological function, biological productivity, or di stribution of soft bottom communities.



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

The most likely effects of a subsea blowout on bent hic communities would be within a few hundred meters of the wellsites. The MMS (2007b) e stimates that a severe subsurface blowout could resuspend and disperse sediments with in a 300-m (984-ft) radius. While coarse sediments (sands) would probably settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) coul d be resuspended for more than 30 days and dispersed over a much wider area. Previous studies characterized surface sediments in the vicinity of the site as about 50% clay and 45% silt (Rowe and Kennicutt, 2009).

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity o f the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise qu ickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles (35 km) from the wellsites and persisting for more than a month (Camilli et al ., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhea d (Joint Analysis Group, 2010c). This observation is supported by Kujawinski et al. (2011 ) in their report that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and were detected up to 186 miles (300 km) from the wellsite at a water depth of 1,000 to 1,200 m (3,280 to 3,937 ft). However, estimated dispersant concentrations in the subsea plume were
below levels known to be toxic to marine life. Whi le the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300-m (984-ft) radius estima ted by MMS (2007a, 2008), depending on its extent, trajectory, and persistence. This c ontact could result in smothering and/or toxicity to benthic organisms. The affected area w ould be recolonized by benthic organisms over a period of months to years (NRC, 2003).

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on soft bottom communities are expected.



### C.2.2 High-Density Deepwater Benthic Communities

As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas that could support high-density chemosyntheti c communities, or features or areas that could support high-density deepwater corals and oth er associated high-density hard bottom communities. Chemosynthetic communities were disco vered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities
are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007; CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities, a nd on shipwrecks. The nearest knownMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 26 

### chemosynthetic community site is located approximat ely 7 miles (11 km) to the northnortheast in MC 853 (Brooks et al., 2009).

The chemosynthetic community assessment included in this Supplemental EP, based on the shallow hazards report by GEMS (2007), did not iden tify any features that could support high-density deepwater benthic communities within 6 10 m (2,000 ft) of the proposed drilling mud/cuttings discharge locations.

IPFs potentially affecting high-density deepwater b enthic communities are effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic communi ties because the diesel fuel would float and dissipate on the sea surface. Because a DP drillin g rig will be used, there will be no anchoring impacts.



### Impacts of Effluent Discharges

The chemosynthetic community assessment included in this Supplemental EP, based on the shallow hazards report by GEMS (2007), did not iden tify any features that could support high-density deepwater benthic communities within 6 10 m (2,000 ft) of the proposed drilling mud/cuttings discharge locations. Monitoring progr ams on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft) of the wellsites, alt hough detectable deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 2005). If high-density deepwater communities are associated w ith the more distant expulsion features and mud volcanoes identified in the hazards survey, significant impacts on these communities
will be avoided because of the distance from the di scharge location.



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

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

Potential impacts of oil on high-density deepwater benthic communities are discussed by MMS (2007b). Although chemosynthetic communities l ive among hydrocarbon seeps, natural seepage is very constant and occurs at low rates co mpared to the potential rates of oil releaseMississippi Canyon Blocks 940, 984, and 985 May 2011

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### from a blowout. In addition, seep organisms requir e unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), imp acts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; change in sediment characteristics; and reduction or loss of one or mo re commercial and recreational fishery habitats. Sublethal effects could be long-lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water temperat ure and diseases).

The potential for a spill to affect deepwater coral s is indicated by preliminary findings from a recent (October 2010) survey of deepwater coral hab itats near the Macondo spill site (BOEMRE, 2010). Government and academic researcher s were working at a site 1,400 m (4,600 ft) deep and approximately 7 miles (11 km) s outhwest of the Macondo wellhead when they observed dead and dying corals with sloughing tissue and discoloration. The study location was about 61 miles (99 km) from the lease area. Much of the soft coral observed in an area measuring about 15 to 40 m (50 to 130 ft) w as covered by what appeared to be a brown substance. Ninety percent of 40 large corals were heavily affected and showed dead and dying parts and discoloration. Another site 40 0 m (1,312 ft) away had a colony of stony corals similarly affected and partially covered wit h a similar brown substance. Until laboratory analyses are conducted, scientists cannot be certai n what caused the impacts. Sediment and coral samples were collected with an ROV and brough t to the surface for analyses. Further testing will also determine if the substance is oil , and if so, whether it is consistent with the release from the Macondo spill.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on deepwater benthic communities are expected.



### C.2.3 Designated Topographic Features

The blocks are not within or near a designated topo graphic feature or a no-activity zone as identified in NTL 2009-G39. The nearest topographi c feature is Sackett Bank, located 45 miles (73 km) northwest of the lease area.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, imp acts on these features would be unlikely due to the distance and the difference in water dep th. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al. , 2001) and typically would not carry a plume up onto the continental shelf edge.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Bottom (P innacle Trend) Stipulation. As defined by NTL 2009-G39, the nearest pinnacle trend blocks are about 92 miles (149 km) from the lease area, along the shelf edge south of Alabama.

There are no IPFs associated with either routine op erations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small fuel spill would float on the surface and would not reach these seafloor features.

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



### C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (L ow-Relief) Stipulation, which applies to Eastern Gulf of Mexico Planning Area leases in wate r depths of 100 m (328 ft) or less. The nearest blocks covered by the live bottom stipulati on, as defined by NTL 2009-G39, are about 125 miles (202 km) from the project area.

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

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



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

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

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

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No crit ical habitat has been designated for these species in the Gulf of Mexico.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

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

sections.

Table 5. Federally-listed endangered and threatened species in the lease area and along the
northern Gulf coast.

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

Marine Mammals Sperm whale Physeter macrocephalus E X

-- None

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

-- None Fin whale Balaenoptera physalus E X a

-- None Humpback whale Megaptera novaeangliae E X a

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

-- None Sei whale Balaenoptera borealis E X a

-- None Sea Turtles Loggerhead turtle Caretta caretta T X X None Green turtle Chelonia mydas T, E b X X None Leatherback turtle Dermochelys coriacea E X X None Hawksbill turtle Eretmochelys imbricata E X X None Kemp’s ridley turtle Lepidochelys kempii E X X None Birds

Piping Plover Charadrius melodus T -- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E -- X Coastal Texas (Aransas National Wildlife Refuge)
Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)
Terrestrial Mammals
Beach m ouse (Alabama, Choctawhatchee, Perdido Key, St. Andrew) Peromyscus polionotus E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = Endangered; T = Threatened.

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

b The green sea turtle is threatened, except for th e Florida breeding population, which is listed as e ndangered.



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

There are no other endangered animals or plants in the Gulf of Mexico that are reasonably likely to be affected by either routine or accident al events. Other species occurring at certainMississippi Canyon Blocks 940, 984, and 985 May 2011

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### locations in the Gulf of Mexico such as the smallto oth sawfish ( Pristis pectinata ), elkhorn coral ( Acropora palmata ), staghorn coral ( Acropora cervicornis ), and Florida salt marsh vole ( Microtus pennsylvanicus dukecampbelli ) are remote from the lease area and highly unlikel y to be affected.



### C.3.1 Sperm Whale (Endangered)

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

Mexico.

The distribution of sperm whales in the Gulf of Mex ico is correlated with mesoscale physical
features such as eddies associated with the Gulf of Mexico Loop Current (Jochens et al., 2008). Sperm whale populations in the north-central Gulf o f Mexico are present there throughout the year (Davis et al., 2000). Results of a multi-year tracking study show female sperm whales typically concentrated along the upper continental slope between the 200- and 1,000-m (656- and 3,280-ft) depth contours (Jochens et al., 2008). Male sperm whales were more
variable in their movements and were documented in water depths greater than 3,000 m (9,843 ft). Generally, groups of sperm whales sigh ted in the Gulf of Mexico during the MMS-funded Sperm Whale Seismic Study (SWSS) consist ed of mixed-sex groups comprising adult females and immatures, and groups of bachelor males. Typical group size for mixed groups was 10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the lease area. Movements of satellite-tracked individuals suggest that this area of the Gulf continental slope is within t he home range of the Gulf of Mexico population (within the 95% utilization distribution ) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include dri lling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of acc idents – a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negl igible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the i ntermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on sper m whales.



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

Noise from routine drilling activities has the pote ntial to disturb sperm whales. Sperm whales appear to have good low-frequency hearing, but the available data do not indicate a consistent response to anthropogenic noise (Jochens et al., 20 08). Noise associated with drilling is relatively weak in intensity, and an individual ani mal’s noise exposure would be transient.
There are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar sources. Due to the limi ted scope, timing, and geographic location of drilling activities, this project would represent a small temporary contribution to the overall noise regime.

The NMFS (2007) analyzed the potential for impacts of drilling-related noise on sperm whales in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central andMississippi Canyon Blocks 940, 984, and 985 May 2011

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### Western Planning Areas of the Gulf of Mexico. The analysis noted that drilling rigs show low sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects i n sperm whales; therefore, these effects are insignificant (NMFS, 2007).

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



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2006). Data concerning the frequency of ves sel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vess el strikes, the BOEMRE has issued NTL 2007-G04, which recommends protected species id entification training and that vessel operators and crews maintain a vigilant watch for m arine mammals and slow down or stop their vessel to avoid striking protected species, a nd requires operators to report sightings of any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a distance of 9 1 m (300 ft) or greater whenever possible. Vessel operators are required to reduce vessel spee d to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel when safety permits. Compliance with this NTL will mini mize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm whales.

The NMFS (2007) analyzed the potential for vessel s trikes and harassment of sperm whales in its Biological Opinion for the Five-Year Oil and Ga s Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. With impleme ntation of the mitigation measures in NTL 2007-G04, NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. T he NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in a ny significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to indivi duals, or have any consequences at the level of the population. With implementation of the vess el strike avoidance measures requirement to maintain a distance of 90 m (295 ft) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales would be r educed to discountable levels.

Helicopter traffic also has the potential to distur b sperm whales. Smultea et al. (2008) documented responses of sperm whales offshore Hawai i to fixed wing aircraft flying at an altitude of 245 m (800 ft). A reaction to the init ial pass of the aircraft was observed during three (12%) of 24 sightings. All three reactions c onsisted of a hasty dive and occurred at less than 360 m (1,180 ft) lateral distance from the air craft. Additional reactions were seen when
aircraft circled certain whales to make further obs ervations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by the aircraft were short-term and pro bably of no long-term biological significance.

While flying offshore in the Gulf of Mexico, helico pters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In th e event that a whale is seen during transit,Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### the helicopter will not approach or circle the anim als. Although responses are possible based on the Smultea et al. (2008) study, the NMFS (2007) concluded that this altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected.



### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Bi ological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Plan ning Areas of the Gulf of Mexico. Oil impacts on marine mammals are discussed by Geraci a nd St. Aubin (1990). For this Supplemental EP there are no unique site-specific i ssues with respect to spill impacts on these
animals.

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

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

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



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

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

Impacts of oil spills on sperm whales can include d irect impacts from oil exposure, as well as indirect impacts due to response activities and mat erials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and phys iological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation ofMississippi Canyon Blocks 940, 984, and 985 May 2011

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### toxic fumes; ingestion of oil (and dispersants) dir ectly or via contaminated prey; and stress from the activities and noise of response vessels a nd aircraft. Complications of the above may lead to dysfunction of immune and reproductive syst ems, physiological stress, declining physical condition, and death. Behavioral response s can include displacement of animals from prime habitat, disruption of social structure, chan ging prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

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

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

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



### C.3.2 Florida Manatee (Endangered)

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

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees, as the lease area is approximately 67 miles (108 km) from the nearest shoreline (Louisiana). As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance wi th NTL 2007-G03 will minimize the potential for marine debris-related impacts on mana tees.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel strikes, which are identified as a threat in the re covery plan for this species (USFWS, 2001). To reduce the potential for vessel strikes, the BOEMRE has issued NTL 2007-G04, which recommends protected species identification trainin g and that vessel operators and crews maintain a vigilant watch for marine mammals and sl ow down or stop their vessel to avoidMississippi Canyon Blocks 940, 984, and 985 May 2011

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### striking protected species, and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL will m inimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

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



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

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

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

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on manatees are expected.



### C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin w hale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but areMississippi Canyon Blocks 940, 984, and 985 May 2011

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### considered rare or extralimital there (Würsig et al ., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.

Due to the rare occurrence of these whales in the G ulf of Mexico and the limited scope and duration of the project, it is highly unlikely that any endangered mysticete would come into contact with any project activities, either routine operations or accidents. The NMFS (2007) did not include any of these mysticete whales as af fected species in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Ce ntral and Western Planning Areas of the Gulf of Mexico. Potential impacts are analyzed in recent lease sale EISs (MMS, 2007b, 2008), and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts would be the same as those discussed below in Section C.3.4

.


### C.3.4 Non-Endangered Marine Mammals (Protected)

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

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

Dwarf and pygmy sperm whales . At sea, it is difficult to differentiate dwarf s perm whales ( Kogia sima ) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as “ Kogia spp.” Both species have a worldwide distribution i n temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mul lin et al., 1991; Mullin, 2007). Either species could occur in the lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked whale ( Ziphius

cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon europaeus ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the most common and Sowerby’s beake d whale is extralimital. Due to the difficulties of at-sea identification, beaked whale s in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undif ferentiated complex ( Mesoplodon spp. and Ziphius spp.). In the northern Gulf of Mexico, they are br oadly distributed in waters greater than 1,000 m (3,281 ft) over lower slope an d abyssal landscapes (Davis et al., 2000). Any of these species could occur in the lease area.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### Delphinids . Fourteen species of delphinids are known from th e Gulf of Mexico, including Atlantic spotted dolphin ( Stenella frontalis ), bottlenose dolphin ( Tursiops truncatus ), clymene dolphin ( Stenella clymene ), false killer whale ( Pseudorca crassidens ), Fraser’s dolphin ( Lagenodelphis hosei ), killer whale ( Orcinus orca ), melon-headed whale ( Peponocephala
electra ), pantropical spotted dolphin ( Stenella attenuata ), pygmy killer whale ( Feresa

attenuata ), short-finned pilot whale ( Globicephala macrorhynchus ), Risso’s dolphin ( Grampus griseus ), rough-toothed dolphin ( Steno bredanensis ), spinner dolphin ( Stenella longirostris ), and striped dolphin ( Stenella coeruleoalba ). The most common non-endangered cetaceans in the deepwater environment are the pantropical spott ed dolphin, spinner dolphin, and clymene dolphin. However, any of these species cou ld occur in the lease area.

IPFs potentially affecting non-endangered marine ma mmals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill represented by the WCD for th is Supplemental EP). Effluent discharges are likely to have negligible impacts on marine mammals due to rapid dispersion, the small area of ocean affected, the intermittent nature of the disc harges, and the mobility of marine mammals. Compliance with NTL 2007-G03 will minimiz e the potential for marine debris-related impacts on marine mammals.



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

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

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



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals, and there is also a risk of vessel strikes. Data concerning the frequency of v essel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vessel s trikes, the BOEMRE has issued NTL 2007-G04, which recommends protected species id entification training and that vessel operators and crews maintain a vigilant watch for m arine mammals and slow down or stop their vessel to avoid striking protected species, a nd requires operators to report sightings of any injured or dead protected species. Vessel oper ators and crews are required to attempt to maintain a distance of 91 m (300 ft) or greater whe n whales are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans a re sighted while a vessel is underway, vessels must attempt to remain parallel to the anim al’s course and avoid excessive speed or abrupt changes in direction until the cetacean has left the area. Vessel operators are required to reduce vessel speed to 10 knots or less when mot her/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel, when safety permits. Compliance withMississippi Canyon Blocks 940, 984, and 985 May 2011

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### this NTL will minimize the likelihood of vessel str ikes as well as reduce the chance for disturbing marine mammals, and therefore no signifi cant impacts are expected.

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



### Impacts of a Small Fuel Spill

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

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

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

Direct physical and physiological effects of exposu re to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via conta minated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 20 10). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significant impacts would be expected.



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

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

issues.

Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and phys iological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) dir ectly or via contaminated prey (or contaminated vegetation, in the case of manatee s); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stre ss, declining physical condition, andMississippi Canyon Blocks 940, 984, and 985 May 2011

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### death. Behavioral responses can include displaceme nt of animals from prime habitat, disruption of social structure, changing prey avail ability and foraging distribution and/or patterns, changing reproductive behavior/productivi ty, and changing movement patterns or migration (MMC, 2010).

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefore, no s ignificant spill impacts on marine mammals are expected.



### C.3.5 Sea Turtles (Endangered/Threatened)

As listed in Supplemental EP Section 6h , five species of endangered or threatened sea turt les may be found near the lease area. Endangered speci es are the leatherback ( Dermochelys

coriacea ), Kemp's ridley ( Lepidochelys kempii ), and hawksbill ( Eretmochelys imbricata ) turtles. The loggerhead turtle ( Caretta caretta ) is a threatened species. The green turtle ( Chelonia mydas ) is listed as threatened, except for the Florida b reeding population, which is listed as endangered. Species descriptions are presented in a recent lease sale EIS (MMS, 2007b).

Leatherbacks and loggerheads are the most likely sp ecies to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtle s are typically inner shelf and nearshore species, unlikely to occur near the lease area as a dults. Hatchlings or juveniles of any of the sea turtles may be present in deepwater areas, incl uding the lease area, where they may be
associated with Sargassum and other flotsam.

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

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

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

• Green and leatherback turtles – Green and leatherba ck turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conser vation Commission, 2010);

• Kemp’s ridley turtles – The main Kemp’s ridley nest ing site is Rancho Nuevo beach, Tamaulipas, Mexico (NMFS et al., 2010). Approximat ely 200 Kemp’s ridley turtles nested on Texas beaches in 2009 (Sea Turtle Restoration Pr oject, 2011). Kemp’s ridley turtlesMississippi Canyon Blocks 940, 984, and 985 May 2011

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### typically do not nest anywhere near the project are a, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nes t anywhere near the project area.

IPFs potentially affecting sea turtles include dril ling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of acc idents (a small fuel spill and a large oil spill represented by the WCD for this Supplemental EP). Effluent discharges are likely to have negligible impacts on sea turtles due to rapid disp ersion, the small area of ocean affected, and the intermittent nature of the discharges. Complia nce with NTL 2007-G03 will minimize the potential for marine debris-related impacts on sea turtles.



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

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

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



### Support Vessel and Helicopter Traffic

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

Helicopter traffic also has the potential to distur b sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential fo r disturbing sea turtles, and no significant impacts are expected.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discusse d in recent EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion for the F ive-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of M exico. For this Supplemental EP, there are no unique site-specific issues with respect to spil l impacts on these animals.

The probability of a fuel spill will be minimized b y Shell’s preventative measures during fuel transfer. In the unlikely event of a spill, implem entation of Shell’s OSRP is expected to mitigate and reduce the potential for impacts on sea turtles

. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Given t he open ocean location of the lease area, the duration of a small spill and opportunity for i mpacts to occur would be very brief.

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

Direct physical and physiological effects of exposu re to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via conta minated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 20 10). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlik ely to affect sea turtle nesting beaches, as the lease area is 67 miles (108 km) from the nearest sh oreline (Louisiana). As explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



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

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

. Supplemental EP Sections 2j and 9b provide detail on spill response measures.

Studies of oil effects on loggerheads in a controll ed setting (Lutcavage et al., 1995) suggest
that sea turtles show no avoidance behavior when th ey encounter an oil slick, and any seaMississippi Canyon Blocks 940, 984, and 985 May 2011

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

The OSRA results summarized in Table 3 predict that some shorelines that support sea turt le nesting could be contacted within 10 to 30 days. T he nearest nesting area of loggerhead turtles is found in St. Bernard Parish, Louisiana, on beaches within the Breton NWR. This area has a contact probability of 1% after 30 days. The modeling also predicts a 1% probability of contacting Florida Panhandle shorelines that suppor t significant loggerhead sea turtle nesting.

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

Data from the recent Macondo spill provides additio nal information about potential impacts of a large oil spill on sea turtles to supplement the analysis presented in the lease sale EIS (MMS, 2007b). According to NMFS (2010a), approxima tely 600 dead turtles have been reported since the Macondo spill. Species include Kemp’s ridley turtles (481 individuals), loggerhead turtles (67 individuals), and green turt les (29 individuals). Oiled turtles include 18 dead individuals and 456 live, oiled animals tha t were either captured or stranded. Also, 278 turtle nests were translocated (271 loggerhead, 4 Kemp’s ridley, and 3 green turtles) and more than 14,000 hatchlings were released. The str andings and captures ranged from the Louisiana/Texas border to Cape San Blas in the Flor ida Panhandle.

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on sea turtles are expected.



### C.3.6 Piping Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along t he
southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of hunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical overwintering habitat has been designated, includin g beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 3 ). Piping Plovers inhabit coastal sandy beaches an d mudflats, feeding by probing for invertebrates at or just bel ow the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in a recent lease sale EIS (MMS, 2007b).Mississippi Canyon Blocks 940, 984, and 985Mayl 2011Environmental Impact Analysis for Supplemental EPPage 42Figure 3. Location of selected environmental features in relation to the lease area. Shown are Essential Fish Habitat (EFH) for coral andcoral reefs; Habitat Areas of Particular Concern (HAPC) for northwestern Gulf of Mexico reefs and banks and spawning Atlanticbluefin tuna; critical habitat for beach mice, Gulfsturgeon, Piping Plover, and Whooping Crane; and the Macondo spill location.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

Section A.9.2 ).



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

The lease area is 69 miles (112 km) from the neares t shoreline inhabited by Piping Plovers.
The OSRA results summarized in Table 3 predict that Texas, Louisiana, and Florida shoreli nes designated as critical habitat for the wintering Pi ping Plover could be contacted by a spill within 30 days. Plaquemines Parish, which has the highest probability of contact for the 10-day and 30-day intervals, includes Piping Plover critical habitat.

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on Piping Plovers are expected.



### C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership [WCEP], 2010). One population winters along the Texas coast at Aransas NWR and
summers at Wood Buffalo National Park in Canada. T his population represents the majority of the world’s population of free-ranging Whooping Cra nes and reached a record population of 270 at Aransas NWR in December 2008 (WCEP, 2010). A non-migrating population has been re-introduced in central Florida, and another re-in troduced population summers in Wisconsin and migrates to the southeastern U.S. for the winte r. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, includ ing coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR a nd adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas N WR is designated as critical habitat for the species ( Figure 3 ). A species description is presented in a recent lease sale EIS (MMS, 2007b).Mississippi Canyon Blocks 940, 984, and 985 May 2011

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



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

A large oil spill is unlikely to affect Whooping Cr anes because the lease area is approximately 445 miles (716 km) from its critical habitat (Arans as NWR, Texas) and the OSRA modeling predicts no contact with shorelines of the Aransas NWR within 30 days.

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

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



### C.3.8 Gulf Sturgeon (Threatened)

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

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

Section A.9.2 ).Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

Potential spill impacts on Gulf sturgeon are discus sed in recent EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion for th e Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. For this Supplemental EP, there are no unique site-specific issues with respect to this species.

The lease area is about 130 miles (209 km) from the nearest Gulf sturgeon critical habitat. The OSRA modeling ( Table 3 ) predicts that a spill in the lease area has a 1% probability of contacting the coastal areas inhabited by Gulf stur geon within 30 days.

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

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



### C.3.9 Beach Mice (Endangered)

Four subspecies of endangered beach mouse ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawatchee, Perdido Key, and St. Andrew beach mouse. Critical habitat has been designated for all four subspecies; Figure 3 shows the critical habitat combined for all four s ubspecies. Species descriptions are provided in a recent lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting subspecies of beach mouse. There are no IPFs associated with routine project activit ies that could affect these animals due to the distance from shore and the lack of any onshore sup port activities near their habitat. A small fuel spill in the lease area would not affect any s ubspecies of beach mouse because a small fuel spill would not be expected to make landfall o r reach coastal waters prior to breaking up (see explanation in Section A.9.2 ).



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

Potential spill impacts on beach mice are discussed in recent EISs (MMS, 2007b, 2008). For this Supplemental EP, there are no unique site-spec ific issues with respect to these species.

The lease area is about 166 miles (267 km) from the nearest beach mouse critical habitat. The OSRA modeling predicts that a spill in the lease ar ea would not contact beach mouse critical habitat within 30 days. (Okaloosa County, Florida, which has a 1% probability after 30 days, does not include any critical habitat.)Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

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



## C.4 Coastal and Marine Birds

C.4.1 Marine and Pelagic Birds

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

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

Common seabird species include Wilson’s Storm-Petre l ( Oceanites oceanicus ), Magnificent Frigatebird ( Fregata magnificens ), Northern Gannet ( Morus bassanus ), Masked Booby ( Sula dactylatra ), Brown Booby ( Sula leucogaster ), Cory’s Shearwater ( Calonectris diomedea ), Greater Shearwater ( Puffinus gravis ), and Audubon Shearwater ( Puffinus lherminieri ). Seabirds are distributed Gulf-wide and are not specifically associated with the lease area.

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



### .
Trans-Gulf migrant birds including shorebirds, wadi ng birds, and terrestrial birds may also be present in the lease area. Migrant birds may use o ffshore structures and platforms for resting, feeding, or as temporary shelter from inclement wea ther (Russell, 2005). Some birds may beMississippi Canyon Blocks 940, 984, and 985 May 2011

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### attracted to offshore structures because of the lig hts and the fish populations that aggregate
around these structures.

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



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

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

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



### Impacts of Support Vessel and Helicopter Traffic

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



### Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discuss ed in recent EISs (MMS, 2007b, 2008). For this Supplemental EP, there are no unique site-spec ific issues with respect to spill impacts on
these animals.

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’sMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 48 

### OSRP will mitigate and reduce the potential for imp acts on marine and pelagic birds. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

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

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



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

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

Pelagic seabirds could be exposed to oil from a spi ll at the project area. Hess and Ribic (2000) reported that terns, storm-petrels, shearwaters, an d jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird densities over the open ocean typically are <10 bir ds/km 2 

### . The number of pelagic birds that could be affected in open, offshore waters would de pend on the extent and persistence of the
oil slick.

The recent Macondo spill provides relevant informat ion about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic species such as the Northern Gannet , Magnificent Frigatebird, and Masked Booby (International Bird Rescue Research Center, 2 010). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on marine and pelagic birds are expected.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 49 

### C.4.2 Shorebirds and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plov er and Whooping Crane) have been discussed previously in Section C.3 . Various species of non-endangered birds are also found along the northern Gulf coast, including diving bir ds, shorebirds, marsh birds, wading birds,
and waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, f lats, dunes, bars, barrier islands, and similar habitats include the Sandwich Tern, Wilson’s Plover , Black Skimmer, Forster’s Tern, Gull-Billed Tern, Laughing Gull, Least Tern, and Royal Tern (US FWS, 2010b). Additional information is presented in recent lease sale EISs (MMS, 2007b, 20 08).

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

The Bald Eagle ( Haliaeetus leucocephalus ) was delisted from its threatened status in the continental United States on June 28, 2007. The Ba ld Eagle is a terrestrial raptor widely distributed across the southern U.S., including coa stal habitats along the Gulf of Mexico. The Gulf coast is inhabited by both wintering migrant a nd resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebirds and coastal n esting birds include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect shorebirds or coastal nesting bi rds, as the lease area is 67 miles (108 km) from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters p rior to breaking up. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on shorebirds.



### Impacts of Support Vessel and Helicopter Traffic

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

Vessel traffic may disturb some foraging and restin g birds. Flushing distances vary among species and individuals (Rodgers and Schwikert, 200 2). The disturbances will be limited to flushing birds away from vessel pathways; known dis tances are from 20 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 f t) for outboard-powered boats (Rodgers and Schwikert, 2002). Flushing distances may be si milar or less for the support vessels to be used for Shell’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreline, so nesting birds, eggs, and chicks will not be disturbed. Vessel operators will use d esignated navigation channels and complyMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 50 

### with posted speed and wake restrictions while trans iting sensitive inland waterways. Due to the limited scope, timing, and geographic extent of drilling activities, any short-term impacts are not expected to be biologically significant to coastal bird populations.

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



### Impacts of Large Oil Spill (WCD)

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

Data from the recent Macondo spill provides additio nal information about the species of coastal birds that may be affected in the event tha t a large oil spill reached coastal habitats; this information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds had been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, more than 2,000 oiled birds have been col lected alive and about 1,200 released (NMFS, 2010a). According to the International Bird Rescue Research Center (2010), bird species that were treated for oiling following the Macondo spill include the following:

• Brown Pelican

• White Pelican

• Masked Booby

• Magnificent Frigatebird

• Laughing Gull

• Herring Gull

• Northern Gannet

• Black Crowned Night Heron

• Tri-colored Heron

• Green Heron

• Cattle Egret

• Snowy Egret

• Reddish Egret

• Least Bittern

• Common Tern

• Royal Tern

• Caspian Tern • Sandwich Tern

• Forsters Tern

• Black Tern

• Gull-billed Tern

• Least Tern

• Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling

• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia RailMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 51 

### According to the USFWS (2010d), species with the la rgest numbers of dead, oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Roya l Tern, Black Skimmer, Least Tern, unidentified Gull, and unidentified Tern. There ar e no reports of Bald Eagle oiling.

Coastal birds can be exposed to oil as they float o n the water’s surface, dive during foraging, or
wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 201 0e). Oil interferes with the water repellency of feathers and can cause hypothermia un der certain conditions. As birds groom themselves, they can ingest and inhale the oil on t heir bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carca sses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the nest or if oil covers the eggs.

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on shorebirds and coastal nesting birds are expected.



## C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

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

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

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; w ater intakes; and two types of accidents (a small fuel spill and a large oil spill [WCD]).Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 52 

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

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



### Impacts of Effluent Discharges

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

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

.
Other discharges in accordance with the NPDES permi t, such as desalination unit brine and uncontaminated cooling water, fire water, and balla st water, are expected to be diluted rapidly and have little or no impact on water colum n biota.



### Impacts of Water Intakes

Seawater will be drawn from the ocean for once-thro ugh, non-contact cooling of machinery on the drilling rig. The estimated intake and disc harge of cooling water is 130,600 BPD (5.48 MGD) and another 130,600 BPD (5.48 MGD) for f ire water. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and e ntrainment of aquatic organisms. Construction of the rig planned for use in this Su pplemental EP, the Noble Danny Atkins

, started prior to July 17, 2006, and therefore is no t subject to the cooling water intake permit requirements of NPDES Permit GMG 290000. If a simi lar type rig is selected, it will comply with all applicable NPDES requirements



### Impacts of a Small Fuel Spill

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

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for imp acts on pelagic communities, including ichthyoplankton. Supplemental EP Sections 2j and 9b provide detail on spill responseMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 53 

### measures. Given the open ocean location of the lea se area, the duration of a small spill and opportunity for impacts to occur would be very brie f.

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

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

communities.



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

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

same water mass.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on pelagic communities and ichthyoplankton are expected.



### C.5.2 Essential Fish Habitat

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

The Gulf of Mexico Fishery Management Council (GMFM C) has prepared Fishery Management Plans for corals and coral reefs, shrimp, stone cra b, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Mana gement Plans (GMFMC, 2005). The EFH for most of these GMFMC-managed species is on the c ontinental shelf in waters shallower than 183 m (600 ft). The shelf edge is the outer b oundary for coastal migratory pelagic fishes, reef fishes, and shrimp. EFH for corals and coral reefs includes some shelf-edge topographicMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 54 

### features on the Texas-Louisiana OCS, the nearest of which is Sackett Bank, located 45 miles (73 km) north-northwest of the lease area.

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

• Atlantic bigeye tuna (juveniles, adults)

• Atlantic bluefin tuna (spawn, eggs, larvae, adults)

• Atlantic skipjack tuna (spawn, adults)

• Atlantic yellowfin tuna (all)

• Atlantic swordfish (all) • Blue marlin (juveniles, adults)

• White marlin (juveniles, adults)

• Sailfish (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Oceanic whitetip shark (all)

• Silky shark (all)

• Longfin mako shark (all)

• Bigeye thresher shark (all)

Recent research indicates the central and western G ulf of Mexico may be important spawning habitat for Atlantic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers m uch of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 3 00,000 km 2 

### (15,000 mi 2 

### ). The prevailing assumption is that Atlantic blue fin tuna follow an annual cycle of foraging in June through March off the eastern Unit ed States and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

Other HAPCs have been identified in the Gulf of Mex ico by the GMFMC (2005). These include the Florida Middle Grounds, Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, and several indi vidual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest of these is Jakkula Bank, located 1 46 miles (236 km)
west of lease area MC 984.

Routine IPFs potentially affecting EFH include (1) drilling rig presence, noise, and lights; (2) effluent discharges; and (3) water intakes. In addition, two types of accidents – a small fuel spill and a large oil spill (WCD) – may impact EFH and fisheries resources.



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

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



### Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminish ing ambient water quality include drilling muds and cuttings, treated sanitary and domestic wa stes, deck drainage, and miscellaneousMississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 55 

### discharges such as desalination unit brine and unco ntaminated cooling water, fire water, and ballast water. Impacts on water quality have been discussed previously. No significant impacts on EFH for highly migratory pelagic fishes are expected from these discharges.



### Impacts of Water Intakes

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



### Impacts of a Small Fuel Spill

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

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

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

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

### (114,793 mi 2 

### ) of the Gulf of Mexico.

A small fuel spill would not affect EFH for corals and coral reefs; the nearest coral EFH is Sackett Bank, located 45 miles (73 km) north-northw est of the lease area. A small fuel spill would float and dissipate on the sea surface and wo uld not contact these features.



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

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

An oil spill in offshore waters would temporarily i ncrease hydrocarbon concentrations on the water surface and potentially the subsurface as wel l. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.Mississippi Canyon Blocks 940, 984, and 985 May 2011

Environmental Impact Analysis for Supplemental EP Page 56 

### A large spill could affect the EFH for many managed species including shrimp, stone crab, spiny lobster, coral and coral reefs, reef fishes, coasta l migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality an d water column biota including phytoplankton, zooplankton, ichthyoplankton, and ne kton. In coastal waters, sediments could be contaminated and result in persistent degradatio n of the seafloor habitat for managed demersal fish and shellfish species.

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

The pinnacle trend area, located 92 miles (149 km) north from the lease area, is designated as EFH under the corals and coral reefs management pla n. An accidental spill would be unlikely
to affect this area. A surface slick would not rea ch these features. Although there are reports of subsurface plumes resulting from the use of subs ea dispersants during the Macondo spill, the distance and difference in water depth are fact ors that would make an impact unlikely. Near-bottom currents in the region are expected to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on EFH are expected.



## C.6 Archaeological Resources

C.6.1 Shipwreck Sites

MC 940, 984, and 985 are in an area with high poten tial for historic shipwrecks. An Archaeological Assessment conducted by C&C Technolo gies, Inc. (2007) detected 106 unidentified sidescan sonar targets, several drag s cars, and other geological features within the survey area. Twenty-three of these sonar targe ts were in MC 940, 984, and 985. There were no sonar contacts with acoustic signature that require archaeological avoidance or further investigation. No shipwrecks were found wi thin MC 940, 984, and 985.

Because there are no historic shipwreck sites in th e lease area, there are no routine IPFs that are likely to affect these resources. Impacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect sh ipwrecks because the oil would float and dissipate on the sea surface.



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

The MMS (2007b) estimated that a severe subsurface blowout could resuspend and disperse sediments within a 300-m (984-ft) radius. Because there are no historic shipwrecks in the lease area, the WCD would not result in any impact on archaeological resources.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise qu ickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles (35 km) from the wellsite and persisting for more than a month (Camilli et al ., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhea d (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not w ell known, a subsurface plume could have the potential to contact shipwreck sites beyon d the 300-m (984-ft) radius estimated by MMS (2007a, 2008), depending on its extent, traject ory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrec ks on the seafloor it could adversely affect their condition or preservation. Should the re be any indication that potential shipwreck sites could be affected, in accordance with NTL 200 5-G07 Shell will immediately halt operations, take steps to ensure that the site is n ot disturbed in any way, and contact the Regional Supervisor, Leasing and Environment, withi n 48 hours of its discovery. Shell would cease all operations within 305 m (1,000 ft) of the site until the Regional Director provides instructions on steps to take to assess the site’s potential historic significance and protect it.

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

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



### C.6.2 Prehistoric Archaeological Sites

With water depths ranging from 1,213 to 1,269 m (3, 978 to 4,164 ft), the wellsites are well beyond the 60-m (197-ft) depth contour used by the BOEMRE as the seaward extent for prehistoric archaeological site potential in the Gu lf of Mexico. Because prehistoric archaeological sites are not found in the lease are a, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehist oric archaeological resources because the oil would float and dissipate on the sea surface.



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

Because prehistoric archaeological sites are not fo und in the lease area, they would not be affected by the physical effects of a subsea blowou t. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and dispe rse sediments within a 300-m (984-ft)
radius.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### Along the northern Gulf coast, prehistoric sites oc cur frequently along the barrier islands and mainland coast and along the margins of bays and ba yous (MMS, 2007b). The OSRA modeling
summarized in Table 3 predicts that Texas, Louisiana, and Florida shorel ines could be contacted by a spill within 30 days. A spill reach ing a prehistoric site along these shorelines could coat fragile artifacts or site features and c ompromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radio carbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations ( e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site fea tures).

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on archaeological resources are expected.



## C.7 Coastal Habitats and Protected Areas

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

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

A small fuel spill in the lease area would be unlik ely to affect coastal habitats, as the lease area is 67 miles (108 km) from the nearest shoreline. A s explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coa stal waters prior to breaking up.



### Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats . Over time with a large number of vessel trips, vessel wakes can erode shorelines along inle ts, channels, and harbors. Support operations, including crew boats and supply boats a s detailed in Supplemental EP Section 14

, may have a minor incremental impact on coastal habi tats or protected areas. Impacts will be minimized by following the speed and wake restricti ons in harbors and channels.



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

Potential spill impacts on coastal habitats are dis cussed in recent EISs (MMS, 2007b, 2008). Coastal habitats inshore of the project area includ e barrier beaches and dunes, wetlands, andMississippi Canyon Blocks 940, 984, and 985 May 2011

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### submerged seagrass beds. For this Supplemental EP, there are no unique site-specific issues with respect to coastal habitats.

The OSRA results summarized in Table 3 predict that shorelines of Texas, Louisiana, and Florida could be affected within 30 days. Plaquemi nes Parish, Louisiana, has the highest probability of contact for the 10-day and 30-day in tervals (4% and 8%, respectively). Two other Louisiana parishes (Terrebonne and Lafourche) may be contacted within 10 days. After 30 days, 11 counties or parishes may be contacted f rom Galveston, Texas, to the Okaloosa County in the Florida Panhandle.

The shorelines within the geographic range predicte d by the OSRA modeling include extensive barrier beaches and wetlands, with submerged seagra ss beds occurring in sheltered areas
behind the barrier islands and in estuaries. Natio nal wildlife refuges and other protected areas along the coast are discussed in the lease sale EIS (MMS, 2007b) and Shell’s OSRP. Coastal wildlife refuges, wilderness areas, and state and n ational parks within the geographic range of the potential shoreline contacts after 30 days incl ude the following:

• Galveston Island State Park

• Brazoria NWR

• Apffel Park

• Seawolf Park

• Old Fort Travis Park

• Atkinson Island Wildlife Management Area (WMA)

• Ft. Anahuac Park

• Anahuac NWR

• McFaddin NWR

• Sea Rim State Park

• J.D. Murphree WMA

• Texas Point NWR

• Sabine NWR

• Cameron Prairie NWR

• LaCassine NWR

• Little Pecan Island Preserve

• Peveto Woods Sanctuary

• Lower Neches WMA

• Rockefeller State Wildlife Refuge
and Game Preserve • Paul J. Rainey WMA

• Marsh Island WMA

• Cypremort Point State Park

• Atchafalaya Delta WMA

• Mandalay NWR

• Isles Dernieres Barrier Islands Refuge

• Pointe Au Chien WMA

• Wisner WMA

• Grand Isle State Park

• Salvador WMA

• Jean Lafitte National Historical Park
and Preserve

• Delta NWR

• Pass a Loutre WMA

• Breton NWR

• St. Bernard State Park

• Biloxi WMA

• Bayou Sauvage NWR

• Gulf Islands National Seashore

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

The level of impacts from oil spills on coastal hab itats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographicMississippi Canyon Blocks 940, 984, and 985 May 2011

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### conditions at the time (MMS, 2007b). Oil that make s it to beaches may be either liquid weathered oil, an oil-and-water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the t ime of landfall. Oil that remains on the beach will thicken as its volatile components are l ost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and othe r materials into its mass. Tar may be buried to varying depths under the sand. On warm days, bo th exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manual ly, mechanically, or both. Some oil can remain on the beach at varying depths and may persi st for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS ( 2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation will experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacte d wetlands are expected to be converted permanently to open-water habitat. The critical co ncentration of oil is that concentration above which impacts to wetlands will be long-term a nd recovery will take longer than two growing seasons, and which causes plant mortality a nd some permanent wetland loss. Critical concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. Louisiana wetlands are assumed to b e more sensitive to oil contact than elsewhere in the Gulf because of high cumulative st ress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshe s may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b).

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on coastal habitats are expected.



## C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfi shes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and summer. In August 2000, the Federal government clo sed two areas in the northeastern Gulf of Mexico to longline fishing (65 Federal Register 472 14, August 1, 2000). The lease is outside of
the closure areas.

Longline gear consists of monofilament line deploye d from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shel f Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in pl ace at regular intervals. It takes 8 to 10 hours to deploy a longline and about the sa me time to retrieve it. Longlines are often set near oceanographic features such as fronts or d ownwellings, with the aid of sophisticated on-board temperature sensors, depth finders, and po sitioning equipment. Vessels areMississippi Canyon Blocks 940, 984, and 985 May 2011

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### 10 to 30 m long, and their trips last from about 1 to 3 weeks. The main homeports for longlining vessels are in Louisiana (Dulac and Veni ce) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. Benthic species targeted by commerci al fishers occur on the upper continental slope, well inshore of the project area. Royal red shrimp are caught by trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Ti lefish are caught by bottom longlining in water depths from about 165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region oc curs in water depths less than 200 m (656 ft) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum platforms o ffshore Texas and Louisiana. The nearby
Mars and Ursa TLPs are known sites of recreational fishing in the region (Continental Shelf Associates, Inc. (2002).

The only routine IPF potentially affecting fisherie s is drilling rig presence (including noise and lights). Two potential accidents are also addresse d below – a small fuel spill and a large oil spill (WCD).



### Impacts of Drilling Rig Presence

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

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



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for imp acts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Given t he open ocean location of the lease area, the duration of a small spill and opportunity for i mpacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small fuel spill. The area of the sea surface with diese l fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vesse ls operating in the lease area. A small fuel spill would not affect coastal water quality becaus e the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

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

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of sp ill response measures. The recent Macondo spill provides information about the potential exte nt of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010c). At its peak on July 12, 2010, closures encompassed 217,821 km 2 

### (84,101 mi 2 

### ), or 34.8% of the U.S. Exclusive Economic Zone (EE Z) in
the Gulf of Mexico.

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



### C.8.2 Public Health and Safety

There are no IPFs associated with routine operation s that are expected to affect public health and safety. Impacts of a small fuel spill and a la rge oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for imp acts. Supplemental EP Sections 2j and 9b provide detail on spill response measures.

A small fuel spill would not have any impacts on pu blic health and safety because it would affect only a small area of the open ocean 67 miles (108 km) from the nearest shoreline and nearly all of the diesel fuel would evaporate or di sperse naturally within 24 hours. Response crews would be equipped with appropriate safety equ ipment to avoid injury and health effects. A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

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

Depending on the spill rate and duration, the physi cal/chemical characteristics of the oil, the meteorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to o il on the water and along the shoreline, through skin contact or inhalation of VOCs. Crude oil is a highly flammable material, and anyMississippi Canyon Blocks 940, 984, and 985 May 2011

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### smoke or vapors from a crude oil fire can cause irr itation. Exposure to large quantities of crude oil may pose a health hazard.

Data from the recent Macondo spill provide relevant information about the types of health issues that may occur in the event of a large oil s pill (Centers for Disease Control and Prevention, 2010a). Wildlife cleaning and rehabil itation workers have reported concerns including scrapes and cuts, itchy or red skin or ra sh, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildlife cleaning workers. Personnel working on offshore ve ssels or providing direct oversight to offshore vessels, including USCG personnel, civilia n contractors, and other responders who were exposed to oil and dispersants, had 7 to 12 ti mes higher prevalences of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers is exposure to seasonal temperature extremes resulting in heat str ess in the summer and hypothermia in the winter. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 

### S such as headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pa in (Solomon and Janssen, 2010). Health effects reported from previous oil spills, such as the Exxon Valdez in 1989, were primarily acute injuries consisting of headaches, throat irri tation, and sore or itchy eyes, but respiratory problems and dermatitis along with chronic airway d isease have also been reported (Solomon and Janssen, 2010).

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



### C.8.3 Employment and Infrastructure

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



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for imp acts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Given t he open ocean location of the lease area, the duration of a small spill and opportunity for i mpacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities , resources, and personnel.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008). For this Supplemental EP, there are no uniq ue site-specific issues with respect to employment and coastal infrastructure. A large spi ll could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it could result in temporary employment as part of the response eff ort; it could result in adverse publicity that affects employment in coastal recreation and t ourism industries; and it could result in another suspension of OCS drilling activities, incl uding service and support operations that are an important part of local economies.

The lease area is 67 miles (108 km) from the neares t shoreline. Based on OSRA modeling as
summarized in Table 3 , Texas, Louisiana, and Florida coastal areas are t he most likely to be contacted by a spill. It is not known whether othe r, more distant coastal areas could be affected if an oil spill persisted for more than 30 days.

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



### C.8.4 Recreation and Tourism

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



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized b y Shell’s preventative measures during routine operations including fuel transfer. In the unlikel y event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for imp acts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Given t he open ocean location of the lease area, the duration of a small spill and opportunity for i mpacts to occur would be very brief.

A small fuel spill in the lease area would be unlik ely to affect recreation and tourism. There
are no known recreational or tourism activities occ urring in the lease area, and as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



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

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

Impacts on recreation and tourism would vary depend ing on the duration of the spill and its fate including the effectiveness of response measur es. A large spill that reached coastalMississippi Canyon Blocks 940, 984, and 985 May 2011

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### waters and shorelines could adversely affect recrea tion and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on OSRA modeling as summarized in Table 3 , Plaquemines Parish, Louisiana, is the area most likely to be contacted by a spill. However, shorel ines from Galveston, Texas, to the Florida
Panhandle could be contacted. These areas include popular beaches and recreational sites along the coast. It is not known whether other, mo re distant coastal areas could be affected if an oil spill persisted for more than 30 days.

In addition to the analysis presented by MMS (2007b , 2008), recent and ongoing studies have explored the economic impacts of the Macondo spill including tourism and “brand” damage (IEM, 2010; Oxford Economics, 2010). The U.S. Trav el Association has estimated the economic impact of the Macondo spill on tourism across the G ulf Coast over a 3-year period at $22.7 billion (Oxford Economics, 2010). There are ongoing efforts to accelerate recovery by informing public perceptions; creating travel incen tives; and providing access to capital, low interest loans, and tax incentives for affected bus inesses (U.S. Travel Association, 2010).

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on recreation and tourism are expected.



### C.8.5 Land Use

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

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



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

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

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9bMississippi Canyon Blocks 940, 984, and 985 May 2011

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### provide detail on spill response measures. Therefo re, no significant spill impacts on land use are expected.



### C.8.6 Other Marine Uses

The lease area is not located within any USCG-desig nated fairway or shipping lane. MC 940, 984, and 985 are not in a designated Military Warni ng Area. Shell will comply with BOEMRE requirements and lease stipulations to avoid impact s on uses of the area by military vessels
and aircraft.

A discontinued industrial waste dump area that was active in the 1970s is located to the west-northwest of the lease area. Shell has prepar ed a BOEMRE-approved plan for “Waste Barrel Avoidance and Release Response in the Missis sippi Canyon Area” that applies to operations that could cause a disturbance of a seaf loor barrel. Shell’s over-arching policy is to avoid barrel contact. The plan specifies a safe st and-off distance from the waste barrels of 10 m (33 ft) and requires that potential impact loc ations be surveyed with an ROV to maximize barrel avoidance. In the unlikely event that conta ct is suspected or has been made with any wastes from a barrel, the plan specifies actions to be taken for the topside safety of personnel handling the equipment. The plan also outlines bar rel impact reporting procedures. There will be no anchor impacts because a DP semisubmersible w ill be used for drilling.

There are no IPFs from routine project activities t hat are likely to affect shipping or other marine uses. Physical disturbance to the existing well will be prevented by the 152-m (500-ft)
avoidance zone established around these features. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have an y impacts on other marine uses, as the spill and response activities would be mainly within the lease area and the duration would be brief.



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

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

In the event of a large spill requiring numerous ve ssels in the area, coordination would be required to ensure that no anchoring or seafloor-di sturbing activities occur near the existing pipelines and flowlines. In addition, the procedur es detailed in Shell’s Waste Barrel Avoidance and Release Response Plan would be adhered to durin g response to any spill in the area.

A blowout resulting in a large oil spill (WCD) is a n extremely rare event, and the probability of such an event will be minimized by Shell’s well con trol and blowout prevention measures as
detailed in Supplemental EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Supplemental EP Sections 2j and 9b provide detail on spill response measures. Therefo re, no significant spill impacts on other marine uses are expected.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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## C.9 Cumulative Impacts

For purposes of NEPA, cumulative impact is defined as “the impact on the environment which results from the incremental impact of the action w hen 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). Any single activity or action may have a negligible impact(s) by itself, but when combined with impacts from other activities in the same area and/or time period, substantial impacts m ay result.

Prior Studies . MC 984 and 985 were acquired in Lease Sale # 178 -1 on 18 March 2001. MC 940 was acquired in Lease Sale #205 in October, 2007. Prior to the lease sales, MMS prepared a multisale EIS in which it analyzed the e nvironmental impact of activities that might
occur in the multi-lease-sale area. The MMS also r ecently analyzed the cumulative impacts of OCS development activities similar to those planned in this Supplemental EP in several documents. The level and types of activities plann ed in Shell's Supplemental EP are within the range of activities described and evaluated in the Final EIS for Gulf of Mexico OCS Oil and Gas Lease Sales 2007-2012: Western Planning Area Sales 204, 207, 210, 215, and 218, and Central Planning Area Sales 205, 206, 208, 213, 216, and 22 2 (MMS, 2007b), as updated by a 2008 Final Supplemental EIS for Gulf of Mexico OCS Oil a nd Gas Lease Sales 2009-2012: Central Planning Area Sales 208, 213, 216, and 222 and West ern Planning Area Sales 210, 215, and 218 (MMS, 2008). Past, present, and reasonably foresee able activities were identified in the
cumulative effects scenario. These documents are i ncorporated by reference.

Description of Activities Reasonably Expected to Oc cur in the Vicinity of Project Area . Shell currently is unaware of any projects that are plann ed to occur in lease blocks adjacent to those included in this Supplemental EP.

Cumulative Impacts of Activities in the Supplementa l EP . The MMS (2007b) multi-lease-sale EIS included a lengthy discussion of cumulative imp acts, which analyzed the environmental and socioeconomic impacts from the incremental impa ct of the 11 proposed lease sales, in addition to all activities (including non-OCS activ ities) projected to occur from past, proposed, and future lease sales during the 40-year period of 2007 to 2046 (see EIS page 4-301). The EIS considered exploration, delineation, and developmen t wells; platform installation; service-vessel trips; and oil spills. The EIS exam ined the potential cumulative effects on each specific resource for the entire Gulf of Mexico.

The level and type of activity proposed in Shell’s Supplemental EP are within the range of
activities described and evaluated in the recent mu lti-lease-sale EISs. This EIA incorporates and builds on these analyses by examining the poten tial impacts on physical, biological, and

socioeconomic resources from the work planned in this Supplemental EP, in c onjunction with the other reasonably foreseeable activities expecte d to occur in the Gulf of Mexico, as well as the known impacts from the Macondo spill in MC 252. While another large oil spill could have significant impacts, the numerous new safety measur es implemented by the BOEMRE and further mitigation and safety measures proposed by Shell in its Supplemental EP result in a drilling program that reduces the likelihood of ano ther large spill and improves the effectiveness of any response in the extremely unli kely event that another large spill occurs. Thus, for all impacts, the incremental contribution of Shell’s proposed actions to the cumulative impacts analysis in these prior analyses is not significant.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### C.9.1 Cumulative Impacts to Physical/Chemical Resource s

The work planned in this Supplemental EP is limited in geographic scope and duration, and the impacts on the physical/chemical environment will b e correspondingly limited.

Air Quality

. Emissions from pollutants into the atmosphere from activities are not projected to have significant effects on onshore air quality bec ause of the prevailing atmospheric conditions, emission rates and heights, and resulti ng pollutant concentrations. As the BOEMRE found in the multi-lease-sale EISs, the incr emental contribution of activities similar to Shell’s proposed activities to the cumulative impac ts is not significant and will not cause or contribute to a violation of any national ambient a ir quality standard (MMS, 2007b, 2008). In addition, the cumulative contribution to visibility impairment is also very small (MMS, 2007b, 2008). Since the BOEMRE completed the multi-lease- sale EISs, USEPA has adopted a new short-term NAAQS for nitrogen dioxide. The standar d has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore, emissions from Shell's Supplemental EP are not likely to contribute to violations of any NAAQS onshore.

Climate Change . Carbon dioxide (CO 2 

### ) and CH 4 

### emissions from the project would constitute a small incremental contribution to greenhouse gas em issions from all OCS activities. According to the EIS (MMS, 2007a), estimated CO 2 

### emissions from all OCS activities in the 2007-2012 leasing program are about 0.08% to 0.016% of the gl obal CO 2 

### emissions from fossil fuel combustion. Greenhouse gas emissions may contribut e to climate change, with important effects on temperature, rainfall, frequency of seve re weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Chan ge, 2007). In the Gulf of Mexico, sea level rise is an important issue due to the ongoing losse s in coastal wetlands, particularly in coastal Louisiana. Greenhouse gas emissions from the Suppl emental EP represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the previous EISs. Globally, Shell is working to reduce greenhouse gas emissions by increasing the efficiency of its operations, est ablishing a substantial capability in CO 2 

### capture and storage, and continuing to research and develop technologies that increase efficiency and reduce emissions in hydrocarbon prod uction. Shell’s direct greenhouse gas
emissions in 2009 were 11% lower than in 2008 and a pproximately 35% below the 1990 level (Shell, 2009). Shell’s ongoing efforts to reduce g reenhouse gas emissions should offset any incremental contribution from the Supplemental EP.

Water Quality . Shell’s project will have some minor water quali ty impacts due to the NPDES-permitted discharge of drilling muds and cutt ings, treated sanitary and domestic wastes, excess cement, non-contact cooling water, d eck drainage, desalination unit brine, uncontaminated fire water, and ballast water. Thes e effects are expected to be minor (localized to the area within a few hundred meters of the drilling rig), and temporary (lasting only hours longer than the disturbance or discharge ). Any cumulative effects to water quality are expected to be negligible.

New Information . The only new, potentially significant informatio n available since preparation
of the multi-lease-sale EISs arises from the Macond o spill. The Macondo spill caused short-term, localized air quality impacts, e.g., fr om evaporation of volatile hydrocarbons and ISB of floating oil. Monitoring by the USEPA (2010 ) has found levels of ozone and particulatesMississippi Canyon Blocks 940, 984, and 985 May 2011

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### ranging from “good” to “unhealthy for sensitive gro ups” on USEPA’s Air Quality Index; these
are at levels well below those that would cause sho rt-term health problems. The air monitoring conducted to date has not found any poll utants at levels expected to cause long-term harm (USEPA, 2010). Satellite imagery in dicates that the surface slick from the Macondo spill did reach the lease area (ESRI, 2010) . However, based on the information currently available, there is no reason to expect a ny change in air quality conditions or cumulative impacts from those predicted in the mult i-lease-sale EISs.

The Macondo spill also resulted in water quality im pacts. In addition to the oil slick on the sea surface, plumes of submerged oil droplets were prod uced when subsea dispersants were applied at the wellhead (Camilli et al., 2010; Haze n et al., 2010; Joint Analysis Group, 2010a,b,c). Satellite imagery indicates that the s urface slick from the Macondo spill did reach the lease area (ESRI, 2010), and it is also possibl e that subsurface plumes could have affected water quality in or near the lease area. However, OSAT (2010) reported that, after August 2010, waters and sediments in the deepwater Gulf of Mexico beyond 1.8 miles (3 km)
from the Macondo wellsite were below USEPA acute an d chronic benchmarks for PAHs and were not hypoxic. These observations indicate that baseline environmental conditions in the lease area are unlikely to have been significantly altered by the spill. Prior to the incident, water quality in deep, offshore waters was expected to be good, with low levels of contaminants (Kennicutt, 2000). Based on the infor mation currently available, there is no reason to expect any change in water quality condit ions or cumulative impacts from those predicted in the multi-lease-sale EISs.



### C.9.2 Cumulative Impacts to Biological Resources

The work planned in this Supplemental EP is limited in geographic scope and duration, and the impacts on biological resources will be correspondi ngly limited.

Seafloor Habitats and Biota

. Effects on seafloor habitats and biota from dischar ges of drilling mud and cuttings are expected to be minor and limit ed to a small area. There are no areas that may support high-density deepwater benthic com munities within 610 m (2,000 ft) of the wellsites, in compliance with NTL 2009-G40. Soft b ottom communities are ubiquitous along the northern Gulf of Mexico continental slope, and the extent of benthic impacts during this project is insignificant regionally. As noted in t he multi-lease-sale EISs, the incremental contributions of activities similar to Shell’s prop osed activities to the cumulative impacts is not significant (MMS, 2007b, page 4-325).

Threatened, Endangered, and Protected Species . Threatened and endangered species reasonably likely to occur in the lease area includ e the sperm whale and five species of sea turtles. Potential impact sources include drilling rig presence including noise and lights; marine debris; and support vessel and aircraft traf fic. Potential effects for these species would be limited and temporary, and would be reduced by S hell’s compliance with all BOEMRE-required mitigation measures including NTLs 2007-G03 and 2007-G04. No significant cumulative impacts are expected.

Coastal and Marine Birds . Some birds may be attracted to offshore structur es because of the lights and the fish populations that aggregate arou nd these structures. Birds that frequent platforms may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispe rsion. Shell’s compliance with NTL 2007-G03Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### will minimize the likelihood of debris-related impa cts on birds. Support vessel and helicopter traffic may disturb some foraging and resting birds ; however, it is likely that individual birds would experience, at most, only short-term behavior al disruption. Due to the limited scope, timing, and geographic extent of drilling activitie s, collisions or other adverse effects are unlikely, and no significant cumulative impacts are expected.

Fisheries Resources . Drilling rigs function as FADs for some species of epipelagic fishes; the aggregations of prey fishes may potentially attract predators. These short-term effects are expected to be small given the isolated nature of t he drilling rig and would not be considered a significant impact on pelagic communities, fishery resources, or EFH. Many exploration and production structures occur in the MC lease blocks proposed for the exploration activities. The additional effect of the proposed drilling activity would be negligible.

Coastal Habitats . Due to the distance of the well sites from shore , routine activities are not expected to have any impacts on beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area. The support bases
at Port Fourchon and Boothville are not in a wildli fe refuge or a wilderness area. Support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Im pacts will be minimized by following the speed and wake restrictions in harbors and channels

.

New Information . The only new, potentially significant informatio n available since preparation
of the multi-lease-sale EISs arises from the Macond o spill. The spill has resulted in impacts on biological resources, including visibly oiled and/o r dead birds, marine mammals, and sea turtles, as well as oiling of coastal habitats from approximately the Texas/Louisiana border to the Florida Panhandle. Another large spill could r esult in significant cumulative impacts to these resources. However, for all the reasons disc ussed in the Initial EP, Shell’s NTL 2010-N06 response, the OSRP, and herein, the likelihood of a catastrophic well control event resulting in significant amounts of oil in the water is extremel y remote. Therefore, Shell’s proposed activities are not expected to result in any cumula tive impacts to biological resources affected by the Macondo spill, nor should they have any impa ct on the previously-conducted cumulative impact analyses.

Regarding deepwater benthic communities, the multi- lease-sale EISs (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affe ct benthic communities beyond the immediate vicinity of the wellhead (i.e., due to ph ysical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles (35 km) from the wellsi tes and persisting for more than a month (Camilli et al., 2010). The subsurface plumes appa rently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). Thi s observation is supported by Kujawinski et al. (2011) in their report that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and we re detected up to 186 miles (300 km) from the wellsite at a water depth of 1,000 to 1,20 0 m (3,280 to 3,937 ft). However, estimated dispersant concentrations in the subsea plume were below levels known to be toxic to marine life. While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300-m (984-ft) radius estimated by MMS (2007a, 2008), depending on its extent, trajectory, and persistence.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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### This contact could result in smothering and/or toxi city to benthic organisms. The affected area would be recolonized by benthic organisms over a pe riod of months to years (NRC, 2003).



### C.9.3 Cumulative Impacts to Socioeconomic Resources

The work planned in this Supplemental EP is limited in geographic scope and duration, and the impacts on socioeconomic resources will be correspo ndingly limited.

Archaeological Resources . MC 940, 984, and 985 are on the list of leases w ith a high potential for historic shipwrecks. However, an archaeologica l assessment by C&C Technologies, Inc. (2007) indicated that none of the sonar contacts in the lease area were interpreted as historic shipwrecks. Also, the lease area is well beyond th e 60-m (197-ft) depth contour used by the BOEMRE as the seaward extent for prehistoric archae ological site potential in the Gulf of Mexico. Therefore, Shell’s operations will have no cumulative impacts on historic shipwrecks or prehistoric archaeological resources.

Socioeconomic Resources . The multi-lease-sale EISs analyzed the cumulativ e impacts of oil and gas exploration and development in the lease ar ea, in combination with other impact-producing activities, on commercial fishing, recreational fishing, recreational resources, historical and archaeological resources, land use a nd coastal infrastructure, demographics, and environmental justice (MMS, 2007b, pages 4-359 to 4 -378). The BOEMRE also analyzed the economic impact of oil and gas activities on the Gu lf States, finding only minor impacts in most of Texas, Mississippi, Alabama, and Florida, more s ignificant impact in parts of Texas, and substantial impact on Louisiana.

Shell’s proposed activities will have negligible cu mulative impacts on socioeconomic resources. There are no IPFs associated with routine operation s that are expected to affect public health and safety, employment and infrastructure, recreati on and tourism, land use, or other marine uses. Due to the distance from shore, it is unlike ly that any recreational fishing activity is occurring in the project area, and it is unlikely t hat any commercial fishing activity other than longlining occurs at or near the project area. The project will have negligible impacts on fishing activities.

New Information . The only new, potentially significant informatio n available since preparation of the multi-lease-sale EISs is the Macondo spill. The spill has resulted in impacts on commercial and recreational fishing, recreation and tourism, employment, and public health and safety. The Macondo spill resulted in extensiv e fishery closures in the Gulf of Mexico, peaking at 34.8% of the EEZ in the Gulf of Mexico ( NMFS, 2010c). The U.S. Travel Association has estimated the economic impact of the Macondo sp ill on tourism across the Gulf Coast over a 3-year period at $22.7 billion (Oxford Economics, 2010). Reported health impacts (e.g., among spill response and wildlife rehabilita tion workers) ranged from cuts and scrapes, to upper respiratory symptoms and heat stress, to a cute exposure to hydrocarbons or H 2 

### S (Centers for Disease Control and Prevention, 2010a, b; Solomon and Janssen, 2010). Most of these impacts were temporary in nature, although he alth exposure of clean-up workers could have longer-lasting impacts.

However, for all the reasons discussed in the Initi al EP, Shell’s NTL 2010-N06 response, the OSRP, and herein, the likelihood of a catastrophic well control event resulting in significant amounts of oil in the water is extremely remote. T herefore, Shell’s proposed activities are not expected to result in any cumulative impacts to soc ioeconomic resources affected by theMississippi Canyon Blocks 940, 984, and 985 May 2011

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### Macondo spill, nor should they have any impact on t he previously-conducted cumulative impact analyses.



# D. ENVIRONMENTAL HAZARDS

D.1 Geologic Hazards

The shallow hazards assessment included in this Sup plemental EP, based on the shallow hazards report by GEMS (2007), concludes that the w ellsites are free of any major geological hazards and are suitable for the proposed activitie s. See Supplemental EP Section 6a for supporting geological and geophysical information.



## D.2 Severe Weather

Under most circumstances, weather is not expected t o have any effect on the proposed activities. Extreme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rig. High winds and limited visibility during a severe storm could disrupt communication and suppor t activities (vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes. In the event of a h urricane, procedures in Shell’s Hurricane
Evacuation Plan would be followed.



## D.3 Currents and Waves

A rig-based acoustic Doppler current profiler will be used to continuously monitor the current beneath the rig. Metocean conditions such as sea s tates, wind speed, ocean currents, etc. will also be continuously monitored. Under most circums tances, physical oceanographic conditions are not expected to have any effect on t he proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions ) and large waves were considered in the design criteria for the drilling rig. High waves d uring a severe storm could disrupt support activities (i.e., vessel and helicopter traffic) an d make it necessary to suspend some activities on the drilling rig for safety reasons until the st orm or weather event passes.



# E. ALTERNATIVES

No formal alternatives were evaluated in this EIA. However, various technical and operational options, including the location of the wellsites an d the selection of a drilling unit, were considered by Shell in developing the proposed acti on. There are no other reasonable alternatives to accomplish the goals of this projec t.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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# F. MITIGATION MEASURES

The proposed action includes numerous mitigation me asures required by laws, regulations, and BOEMRE lease stipulations and NTLs. The projec t will comply with all applicable Federal, State, and local requirements concerning air pollut ant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under Shell’s OSRP and will include
the measures described in Supplemental EP Section 2j . Additional pollution prevention measures, beyond those required by 30 CFR Part 250, include the following:

• Health, safety, and environment (HSE) are the prima ry 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 inspe ct 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 th e dock and prior to loading on the boat.

• Preventive maintenance of rig equipment includes vi sual 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 cont ainment, drum storage areas, fuel vents, and fuel storage tanks.

• All used oil and fuel is collected and sent to shor e for recycling.

• Every drain on the rig is assigned a number on a ch ecklist. The checklist is used daily 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 sh ore for disposal.

• The rig is involved in a recycling program for card board, plastic, paper, glass, and
aluminum.

• Fuel hoses are changed on annual basis.

• Spill prevention fittings are installed on all liqu id take-on hoses.

• Waste paint thinner is recycled on board with a sol vent to further reduce hazards of shipping and storage.

• All equipment on board utilizes Envirorite hydrauli c fluid as opposed to hydraulic oil.

• Shell has obtained International Organization for S tandardization (ISO) 14001 certification.

• Shell will use low sulfur fuel (0.05% by weight) to reduce air pollutant impacts.

• Use of a DP rig (no anchors) and high resolution so nar for well location planning will minimize the potential for barrel impact. Shell ha s prepared a BOEMRE-approved plan for “Waste Barrel Avoidance and Release Response in the Mississippi Canyon Area” that applies to anchoring and other operations that coul d cause a disturbance of a seafloor barrel. The plan specifies a safe stand-off distan ce from the waste barrels of 10 m (33 ft) and requires that anchor locations be surveyed with an ROV to maximize barrel avoidance. In the unlikely case that contact is suspected or h as been made with any wastes from a barrel, the plan specifies actions to be taken for the topside safety of personnel handling the equipment. The plan also outlines barrel impac t reporting procedures.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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# G. CONSULTATION

No persons or agencies were consulted regarding pot ential impacts associated with the proposed activities during the preparation of this EIA.



# H. PREPARERS

The EIA was prepared at the direction of Shell Offs hore Inc. by its contractor, CSA International, Inc. Contributors included the foll owing:

• Sylvia Bellone (Regulatory Specialist, Shell Explor ation & Production Co.);

• Lori Downs (Environmental Team Leader, Shell Explor ation & Production Co.);

• Rob Kuehn (Environmental Engineer, Shell Exploratio n & Production Co.);

• Warren Moity (Environmental Specialist, Shell Explo ration & Production Co.);

• Victoria Broje (Spill Response Specialist, Shell Gl obal Solutions US Inc.);

• Steve Truchon (Environmental Ecologist, Shell Globa l Solutions US Inc.);

• Phil Smith (Incident Command Manager, Shell Explora tion & Production Co.);

• Erling Westlein (Environmental Engineer, Shell Expl oration & Production Co.);

• Tracy Albert (Regulatory Specialist, Offshore Techn ical Compliance LLC);

• William Heim (Appraisal Team Leader, Shell Explorat ion & Production Co.);

• Aaron Hildebrandt (Geologist, Shell Exploration and Production Co.);

• Arpad Ozsdolay (Geophysicist, Shell Exploration & P roduction Co.);

• Carlyle Kalloo (Senior Scientist, CSA International , Inc.);

• Neal Phillips, Ph.D. (Senior Scientist, CSA Interna tional, Inc.);

• Deborah Fawcett (Project Scientist II, CSA Internat ional, Inc.);

• Stephen Viada (Senior Scientist, CSA International, Inc.);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist , CSA International, Inc.); and

• Kim Dunleavy (Technical Editor, CSA International, Inc.).



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Biggs, D.C. and P.H. Ressler. 2000. Water column biology, pp. 141-187. In: Continental Shelf Associ ates, Inc. Deepwater Program: Gulf of Mexico Deepwater In formation Resources Data Search and Literature Synthesis. Volume I: Narrative Report. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2000-049.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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Boehm, P., D. Turton, A. Raval, D. Caudle, D. Frenc h, N. Rabalais, R. Spies, and J. Johnson. 2001. Deepwater program: Literature review, environmental risks of chemical products used in Gulf of Mexico deepwater oil and gas operations. Volume I: Technical report. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2001-011. 326 pp.
Bromwich, M.R. 2010. Decision memorandum for the Secretary: Report regarding the current suspension of certain offshore permitting and drill ing activities on the outer continental shelf. October 1, 2010. Bureau of Ocean Energy Regulation , Management and Enforcement, Washington, DC. http://www.doi.gov/news/pressreleases/loader.cfm?cs Module=security/getfile&PageID=6470

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Brooke, S., and W.W. Schroeder. 2007. State of de ep coral ecosystems in the Gulf of Mexico region: Texas to the Florida Straits, pp. 271-306. In: S.E . Lumsden, T.F. Hourigan, A.W. Bruckner, and G. Dorr (eds.), The State of Deep Coral Ecosystems of the United States. NOAA Tech. Memo. CRCP-3. Silver Spring, MD. 365 pp.
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C&C Technologies, Inc. 2007. Archaeological Asses sment Report, Blocks 895-898, 939-942 & 983-986, Mississippi Canyon Area. Project No. 072657-072954

. Camilli, R., C.M. Reddy, D.R. Yoerger, B.A.S. Van M ooy, M.V. Jakuba, J.C. Kinsey, C.P. McIntyre, S.P. Sylva, and J.V. Maloney. 2010. Tracking hydrocarbon plum e transport and biodegradation at Deepwater Horizon . Science DOI: 10.1126/science.1195223.
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Centers for Disease Control and Prevention. 2010a. Deepwater Horizon response: NIOSH ongoing
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Centers for Disease Control and Prevention. 2010b. Health Hazard Evaluation of Deepwater Horizon Response Workers, HETA 2010-0115. Interim Report # 6A. 11 pp. http://www.cdc.gov/niosh/hhe/pdfs/interim_report_6. pdf
Clapp, R.B., R.C. Banks, D. Morgan-Jacobs, and W.A. Hoffman. 1982a. Marine birds of the southeastern
United States and Gulf of Mexico. Part I. Gaviifo rmes through Pelicaniformes. U.S. Fish and Wildlife Service, Office of Biological Services, Wa shington, DC. FWS/OBS-82/01. 637 pp.
Clapp, R.B., D. Morgan-Jacobs, and R.C. Banks. 198 2b. Marine birds of the southeastern United States
and Gulf of Mexico. Part II. Anseriformes. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, DC. FWS/OBS-82/20. 492 pp.
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and Gulf of Mexico. Part III. Charadriiformes. U .S. Fish and Wildlife Service, Office of Biological Services, Washington, DC. FWS/OBS-83/30. 853 pp.Mississippi Canyon Blocks 940, 984, and 985 May 2011

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Collard, S.B. and C. Way. 1997. Chapter 5 – The b iological environment. In: Science Applications International Corporation (ed.), Northeastern Gulf of Mexico Coastal and Marine Ecosystem Program: Data Search and Synthesis; Synthesis Repor t. U.S. Department of the Interior, U.S. Geological Survey, Biological Resources Divisi on and Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. USGS/BRD/CR-19 97-0005. OCS Study MMS 96-0014. 313 pp.
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Witherington, B.E. 1997. The problem of photopoll ution for sea turtles and other nocturnal animals, pp. 303-328. In: J.R. Clemmons and R. Buchholz (ed s.), Behavioral Approaches to Conservation in the Wild. Cambridge University Press, Cambridge , England. Würsig, B., S.K. Lynn, T.A. Jefferson, and K.D. Mul lin. 1998. Behaviour of cetaceans in the northern Gulf of Mexico relative to survey ships and aircraft. A quatic Mammals 24:41-50.
Würsig, B., T.A. Jefferson, and D.J. Schmidly. 200 0. The Marine Mammals of the Gulf of Mexico. Texa s A&M University Press, College Station, TX. 232 pp.SECTION 19: Administrative Information

A. Exempted Information Description (Public Information Copies Only)

The following attachments were excluded from the public information copies of this plan:

1b. OCS Plan Information form – Bottom hole locations & proposed total depth 2j. Blowout Scenario – confidential information for NTL 2010 N06 calculation 3a. Geologic Description 3b. Structure Contour Maps 3c. Interpreted 2D or 3D seismic line(s) 3d. Cross Section(s) 3e. Shallow Hazards Report
3f. Shallow Hazards Assessment – confidential data 3g. High-Resolution Seismic Lines & Top Hole Progs 3h. & 3i. Stratigraphic Column with Time vs. depth table

B. Bibliography

3⁄4 GEMS prepared a Geologic, Stratigraphic, and Archeological Assessment on Blocks 940, 984, and 985 of Mississippi Canyon in October 2007, Project Number 0507-1331.

3⁄4 C&C Technologies conducted an Archeological Assessment Report in October 2007 on Mississippi Canyon Blocks 895-898, 939-942, and 983-986, Project Number 072657-072954.