UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of DOCD

Control # - S-07675

Type - Supplemental Development Operations Coordinations Document

Lease(s) - OCS-G08496 Block - 657 Mississippi Canyon Area

Operator - Shell Offshore Inc.

Drill Wells C-4, C-5

Not Found

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

should be addressed in an Environmental Assessment.

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

Tonya Jez

Plan Coordinator

G08496/MC/657

G08496/MC/657

317 FNL, 4213 FEL

310 FNL, 4220 FEL

G08496/MC/657

G08496/MC/657

WELL/C-4

WELL/C-5

Site Type/Name Botm Lse/Area/Blk Surface Location Surf Lse/Area/Blk

Description -

Rig Type -

Subject:

From:

September 22, 2014
Shell Offshore Inc.

P. O. Box 61933

New Orleans, LA 70161-1933

United States of America

Tel +1 504 425 7215

Fax +1 504 425 6747

Email sylvia.bellone@shell.com

Public Information Copy

April 17, 2014 

 

Ms. Michelle Uli, Plans Supervisor 

Bureau of Ocean Energy Management 

Office of Field Operations 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

 

Attn: Plans Section – GM 1053C 

SUBJECT: Supplemental Development Operations Coordination Document 

 Mississippi Canyon Block 657, OCS-G 8496 

 Offshore Louisiana 

 

Dear Ms. Uli: 

In compliance with 30 CFR 550.221 and NTLs 2008-G04 and 2009-G27, giving Development Plan guidelines, 

Shell Offshore Inc. (Shell) requests your approval of this Supplemental Development Operations Coordination 

Document (DOCD) to add two subsea wells and associated infrastructure. Operations are expected to begin 

operations in February 2015. The cost recovery fee is attached to the proprietary copy of the plan. 

We are providing the following to accompany your review of this plan: Geologic, Stratigraphic and 

Archaeological Assessment of Blocks 573 (OCS-G 23521) and 617 (open), DeSoto Canyon Area, Gulf of Mexico 

prepared by GEMs, Project No. 0313-2213a,b, dated July 25, 2013. 

Should you have any questions or require additional information, please contact Tracy Albert at 504.425.4652 

or tracy.albert@shell.com. 

Sincerely, 

Sylvia A. Bellone 

Page 1 Public Information Copy
REVISIONS TABLE 

Date of Request Plan Section What was Corrected Date Resubmitted

RFI No. 1

5/7/2014 Section 9 Comparison table 5/8/2014

RFI No. 2

5/28/2014 Section 2j Proprietary data 6/6/2014

RFI No. 3

6/2/2014 Section 1

Section 6

Section 18

BOEM Form Lease

Corrected ESR Map

Corrected anchor radius 

in EIA

 6/9/2014

RFI No. 4

6/5/2014 Section 1 Add moored rig 6/5/2014

RFI No. 5

6/11/2014 Section 2j Proprietary data 6/11/2014

RFI No. 6

6/16/2014 Section 7 Tables 7A/7B 6/24/2014

RFI No. 7

6/18/2014 Section 2j & 9

Section 6 & 19

WCD Number

Provided additional Arch 

survey info

 6/19/2014

 6/26/2014

RFI No. 8

7/09/2014 Section 6 & 19 Provide additional Arch 

survey

 7/11/2014

RFI No. 9

8/14/2014 Provide full copy of plan 8/18/2014

Page 2 Public Information Copy
 

SHELL OFFSHORE INC. 

Supplemental Development Operations Coordination Document 

for 

Mississippi Canyon Block 657, OCS-G 8496

PUBLIC INFORMATION COPY 

APRIL 2014

PREPARED BY: 

Tracy W. Albert 

Regulatory Specialist 

504.425.4652 

tracy.albert@shell.com

Page 3 Public Information Copy
SUPPLEMENTAL DOCD 

MISSISSIPPI CANYON BLOCK 657, OCS-G 8496 

TABLE OF CONTENTS 

SECTION 1: PLAN CONTENTS 

SECTION 2: GENERAL INFORMATION 

SECTION 3: GEOLOGICAL AND GEOPHYSICAL 

SECTION 4: HYDROGEN SULFIDE - H2S 

SECTION 5: MINERAL RESOURCE CONSERVATION 

SECTION 6: BIOLOGICAL, PHYSICAL AND SOCIOECONOMIC INFORMATION 

SECTION 7: WASTE AND DISCHARGE INFORMATION 

SECTION 8: AIR EMISSION INFORMATION 

SECTION 9: OIL SPILL INFORMATION 

SECTION 10: ENVIRONMENTAL MONITORING 

SECTION 11: LEASE STIPULATIONS 

SECTION 12: ENVIRONMENTAL MITIGATION MEASURES 

SECTION 13: RELATED FACILITIES AND OPERATIONS INFORMATION 

SECTION 14: SUPPORT VESSELS AND AIRCRAFT 

SECTION 15: ONSHORE SUPPORT FACILITIES INFORMATION 

SECTION 16: SULPHUR OPERATIONS 

SECTION 17: COASTAL ZONE MANAGEMENT ACT INFORMATION 

SECTION 18: ENVIRONMENTAL IMPACT ANALYSIS 

SECTION 19: ADMINISTRATIVE INFORMATION 

Page 4 Public Information Copy
ACRONYMS AND ABBREVIATIONS 

ADIOS Automated Data Inquiry for Oil Spills 

APD Application for Permit to Drill 

bbl barrel 

BOEM Bureau of Ocean Energy Management 

BOEMRE Bureau of Ocean Energy Management, 

Regulation and Enforcement 

BOPD barrels of oil per day (bbl/day) 

BSEE Bureau of Safety and Environmental 

Enforcement 

CFR Code of Federal Regulations 

CH4 methane 

CO carbon monoxide 

CO2 carbon dioxide 

DOCD Development Operations Coordination 

Document 

DPS distinct population segment 

EFH Essential Fish Habitat 

EIA Environmental Impact Analysis 

EIS Environmental Impact Statement 

EFL Electrical flying lead 

ESA Endangered Species Act 

FAD fish-attracting device 

GMFMC Gulf of Mexico Fishery Management 

Council 

H2S hydrogen sulfide 

HAPC Habitat Area of Particular Concern 

HFL Hydraulic flying leads 

IPF impact-producing factor 

MARPOL International Convention for the 

Prevention of Pollution from Ships 

MC Mississippi Canyon 

MMC Marine Mammal Commission 

MMPA Marine Mammal Protection Act 

MMS Minerals Management Service 

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 

NO2 nitrogen dioxide 

NOx nitrogen oxides 

NPDES National Pollutant Discharge Elimination 

System 

NPS National Park Service 

NRC National Research Council 

NTL Notice to Lessees and Operators 

NWR National Wildlife Refuge 

OCS Outer Continental Shelf 

OCSLA Outer Continental Shelf Lands Act 

OSAT Operational Science Advisory Team 

OSRA Oil Spill Risk Analysis 

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 

SEA Site-Specific Environmental Assessment 

Shell Shell Offshore Inc. 

SO2 sulfur dioxide 

SOx sulfur oxides 

SFL Steel flying leads 

SWSS Sperm Whale Seismic Study 

TLP tension leg platform 

U.S.C. United States Code 

USCG U.S. Coast Guard 

USDOI U.S. Department of the Interior 

USEPA U.S. Environmental Protection Agency 

USFWS U.S. Fish and Wildlife Service 

VOC volatile organic compound 

WCD worst case discharge 

WCEP Whooping Crane Eastern Partnership 

WMA Wildlife Management Area 

Page 5 Public Information Copy
SECTION 1: PLAN CONTENTS 

A. DESCRIPTION, OBJECTIVES & SCHEDULE 

Shell Offshore Inc. (Shell) is submitting this Supplemental DOCD (DOCD/plan) for Mississippi Canyon Block 

657, OCS-G 8496. This plan is for the drilling and completion of well C-4 and back-up well C-5. The well(s) 

will be drilled and completed in accordance with 30 CFR Subpart D. If the wells are unsuccessful, they will be 

permanently plugged and abandoned in accordance with the Bureau of Safety and Environmental Enforcement 

(BSEE) regulations. This lease has been developed in plans N-7524 DOCD and R-3944 RDOCD. Well No. 1 

was plugged and abandoned; wells C-2 and C-3 are producing wells flowing back to BP’s Na Kika host. 

The drilling activities are planned to commence on or about February 2015 and last approximately 155 days to 

drill and complete the first well, and January 2016 for the drilling and completion of the second well. The 

timeframe for these drilling activities is an estimate based on the best available information regarding downhole 

conditions likely to be encountered while drilling each well and are not intended to be a limitation. 

The lease area is 84 statute miles from the nearest shoreline, 151 statute miles from the onshore support 

base at Port Fourchon, Louisiana and 212 statute miles from the helicopter base at Amelia, Louisiana. Water 

depth at the well sites is approximately 7,553’ (Attachment 1A). 

At the time of this filing, a drilling rig has not been selected. Therefore, we are providing information for the 

three types of rigs available in Shell’s fleet: a moored semi-submersible, a dynamically positioned (DP) semisubmersible and a drill ship. The selected rig will be a self-contained drilling vessel with accommodations for a 

crew which include quarters, galley and sanitation facilities. The drilling activities will be supported by the 

support vessels and aircraft as well as onshore support facilities as listed in Sections 14 and 15 of this plan. 

Shell has employed or contracted with trained personnel to carry out its exploration activities. Shell is 

committed to local hire, local contracting and local purchasing to the maximum extent possible. Shell personnel 

and contractors are experienced at operating in the Gulf of Mexico and are well versed in all Federal and State 

laws regulating operations. Shell’s employees and contractors share Shell’s deep commitment to operating in a 

safe and environmentally responsible manner. 

Shell, through its parent and affiliate corporations, has extensive experience safely exploring for oil and gas in 

the Gulf of Mexico. Shell will draw upon this experience in organizing and carrying out its planned MC 657 

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

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

competence. In the unlikely event of a spill, Shell’s Regional Oil Spill Response Plan (OSRP) is designed to 

contain and respond to a spill that meets or exceeds the worst case discharge (WCD) as detailed in Section 9 of 

this plan. The WCD does not take into account potential flow mitigating factors such as well bridging, 

obstructions in wellbore, reservoir barriers, or early intervention. We continue to invest in research and 

development to improve safety and reliability of our well systems. All operations will be conducted in 

accordance with applicable federal and state laws, regulations and lease and permit requirements. Shell will 

have trained personnel and monitoring programs in place to ensure such compliance. 

B. WELL LOCATIONS 

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

The pipelines/flowlines mentioned in this plan will be Right-of-Way pipelines and covered under separate 

application to BSEE. Jumpers, sled and tree are addressed in Attachment 1C.1. 

Page 6 Public Information Copy
C. GENERAL RIG SAFETY AND POLLUTION FEATURES 

The rig, once selected, will comply with all of the regulations of the American Bureau of Shipping (ABS), 

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

will be conducted under the provisions of 30 CFR, Part 250, Subpart D and other applicable regulations and 

notices, including those regarding the avoidance of potential drilling hazards and safety and pollution 

prevention control. Such measures as inflow detection and well control, monitoring for loss of circulation and 

seepage loss and casing design will be our primary safety measures. Primary pollution prevention measures 

are contaminated and non-contaminated drain system, mud drain system and oily water processing. The rig 

will have Operating Procedures and Job Safety Analysis for any fuel, base oil or SBM transfers. 

DRAIN SYSTEM POLLUTION FEATURES 

Drains are provided on the rig in all spaces and on all decks where water or oil can accumulate. The drains 

are divided into two categories, non-contaminated and contaminated. All deck drains are fitted with a 

removable strainer plate to prevent debris entering the system. 

Deck Drainage from rainfall, rig washing, deck washing, and runoff from curbs and gutters, including drip 

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

1) Non-contaminated Drains 

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

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

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

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

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

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

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

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

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

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

drain. 

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

deployment as appropriate) and reported immediately. 

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

are in place as needed to ensure a proper seal. 

2) Contaminated Drains 

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

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

processing. 

3) Oily Water Processing 

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

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

the MODU, an oil record log will be kept according to instructions included in the log. Any and all pollution 

pans are subjected to a sheen test before being pumped out. If the water passes the sheen test then it is 

pumped over board. If it does not pass the sheen test then the water/oil mixture is pumped to a dirty oil tank 

and sent to shore for disposal. All waste oil that is sent in to be disposed of is recorded in the MODU’s oil log 

book. 

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

Page 7 Public Information Copy
4) Lower Hull Bilge System 

• The main bilge system is designed to drain the pontoons. They are usually Gould’s electrically driven, 

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

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

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

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

for high and low levels. 

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

also used for emergency bilge pump in the event of the main pump room flooding. 

• Alternate means of pumping the bilges in each pontoon pump room include the use of: 

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

• Portable submersible pumps 

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

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

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

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

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

5) Emergency Bilge System 

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

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

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

6) Oily Water Drain/Separation System

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

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

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

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

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

and are subjected to sheen tests before discharge as well. 

7) Drain, Effluent and Waste Systems 

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

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

or non-hazardous drains from nonhazardous areas. 

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

areas, the drainage systems are segregated. 

• The rig’s drainage system ties into oily water separators that take out elements in the drainage that 

could harm the environment. This is part of rig contractor’s initiative to be good stewards of the 

environment. The oily water separators divide the drainage system into these sections below. 

8) Rig Floor Drainage

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

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

the skimmer tank it is drained to one of the column dirty oil tank systems where it is then sent through 2 

separators and cleaned further to reduce oil content to <15 ppm.

Page 8 Public Information Copy
9) Columns #3 & 4 

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

columns. The separators in these columns go through three cycles of circulation and remove oil to <15 ppm, 

then discharge the clean product to sea. 

10) Main Engine Rooms 

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

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

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

11) Helideck Drains 

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

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

helideck structure. 

Operating configurations are as follows: 

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

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

 The oily water collection tank overflow valve is closed. 

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

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

performed. Water is pumped out the skimmer tanks down the shunt line. The oil containment side is 

pumped out into 550 gal tote tanks. 

 The BOP test area drains are normally lined-up to drain overboard. 

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

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

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

ppm. 

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

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

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

discharges water overboard from the water side and oil is pumped out into a 550 gallon tote tank on 

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

Page 9 Public Information Copy
D. Storage Tanks - Transocean Nautilus (or similar moored rig) 

Type of Storage 

Tank

Type of 

Facility

Tank 

Capacity 

(Bbls)

Number of

Tanks

Total

Capacity (Bbls) Fluid Gravity 

(Specific)

Main Diesel Storage 

Tank 

Drilling Rig 16,569 bbls 2 33,138 Marine Diesel (0.87 SG)

Diesel Settling Tank Drilling Rig 837 bbls 2 1,674 Marine Diesel (0.87 SG)

Diesel Day Tank Drilling Rig 837 bbls 2 1,674 Marine Diesel (0.87 SG)

Emergency Diesel 

Generator Tank

Drilling Rig 101 bbls 1 101 Marine Diesel (0.87 SG)

Lube Oil Tank Aft Drilling Rig 182 bbls 1 182 Lube Oil (0.93 SG)

Lube Oil Tank Fwd Drilling Rig 182 bbls 1 182 Lube Oil (0.93 SG)

Hyd. Oil Tank Aft Drilling Rig 63 bbls 1 63 Hydraulic Oil (0.93 SG)

Synthetic Drilling 

Base Fluid 

Drilling Rig 9,190 bbls 2 18,380 Synthetic Base Oil 

Active Port Mud 

Tanks

Drilling Rig 500 bbls 6 3,00 Drilling Mud 

Active Stb Mud 

Tanks

Drilling Rig 500 bbls 6 3,000 Drilling Mud

Process Pit Tanks Drilling Rig 34 bbls 12 408 Drilling Mud

Trip Tanks Drilling Rig 100 bbls 3 300 Drilling Mud

Reserve Mud Tanks Drilling Rig 1,500 bbls 6 9,000 Drilling Mud

Slug Tanks Drilling Rig 100 bbls 4 400 Drilling Mud

Crude oil storage Drilling Rig 25,000 bbls 4 100,000 Crude

Storage Tanks – Noble Jim Day DP (or similar Semi-Submersible)

Type of Storage 

Tank

Type of 

Facility

Tank 

Capacity 

(Bbls)

Number of

Tanks

Total

Capacity (Bbls) Fluid Gravity (Specific)

Diesel Tank in 

stbd 1 80% fill in 

all hull tanks

Drilling Rig 3597 1 Marine Diesel (0.91 SG)

Diesel Tank in 

stbd 2

Drilling Rig 2713 1 Marine Diesel (0.91 SG)

Diesel Tank in 

stbd 3

Drilling Rig 3456 1 Marine Diesel (0.91 SG)

Diesel Tank in 

stbd 4

Drilling Rig 653 1 Marine Diesel (0.91 SG)

Diesel Tank in 

port 1

Drilling Rig 2090 1 Marine Diesel (0.91 SG)

Diesel Tank in 

port 2

Drilling Rig 1366 1 Marine Diesel (0.91 SG)

Diesel Tank in 

port 3

Drilling Rig 4787 1 Marine Diesel (0.91 SG)

Diesel Tank in 

port 4

Drilling Rig 3456 1 Marine Diesel (0.91 SG)

Total storage in 

hull tanks

Drilling Rig 22118 Marine Diesel (0.91 SG)

Diesel Settling 

Tanks

Drilling Rig 129 1 129 Marine Diesel (0.91 SG)

Diesel Settling 

Tanks

Drilling Rig 129 1 129 Marine Diesel (0.91 SG)

Diesel Settling 

Tanks

Drilling Rig 139 1 139 Marine Diesel (0.91 SG)

Diesel Settling 

Tanks

Drilling Rig 129 1 129 Marine Diesel (0.91 SG)

Page 10 Public Information Copy
Noble Don Taylor (or similar Drillship) 

Type of Storage 

Tank

Type of

Facility

Tank

Capacity (bbls)

Number of

Tanks

Total

Capacity (bbls)

Fluid

Gravity (Specific)

Fuel oil Drilling Rig 2,889 4 11,556 Marine Diesel (0.91 SG)

Fuel oil Drilling Rig 3,225 4 12,900 Marine Diesel (0.91 SG)

Fuel oil Drilling Rig 2,887 4 11,548 Marine Diesel (0.91 SG)

Fuel oil Drilling Rig 2,680 4 10,720 Marine Diesel (0.91 SG)

Fuel oil Drilling Rig 178 8 1,424 Marine Diesel (0.91 SG)

E. Pollution Prevention Measures 

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

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

Shell has provided this information as part of its response to 1(c) above. 

F. Additional Measures 

 

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

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

are reminded daily to inspect work areas for safety issues as well as potential pollution issues. 

 All tools that come to and from the rig have their pollution pans inspected and cleaned, and plug 

installation confirmed prior to leaving the dock and prior to loading on the boat. 

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

on a routine scheduled basis. 

 All pollution pans on rig are inspected daily. 

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

storage tanks. 

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

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

 All trash containers are checked and emptied daily, and trash containers are kept covered. Trash is 

collected in a compactor and shipped to shore for disposal. 

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

 Fuel hoses are changed on an annual basis. 

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

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

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

G. Description of Previously Approved Lease Activities 

This lease has been developed in plans N-7524 DOCD and R-3944 RDOCD. Well No. 1 was plugged and 

abandoned; wells C-2 and C-3 are producing wells flowing back to BP’s Na Kika host. 

Page 11 Public Information Copy
Attachment 1A

Bathymetry and Surface 

Locations

Page 12 Public Information Copy
Proprietary data

Attachment 1B

Bottom Hole Locations

Page 13 Public Information Copy
Attachment 1C

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

Bureau of Ocean Energy Management OMB Approval Expires: 12/31/2014 

OCS PLAN INFORMATION FORM 

General Information

Type of OCS Plan: Exploration Plan (EP) X DOCD

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

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

New Orleans, LA 70161-1933 Phone Number: (504) 425-4652

E-Mail Address: tracy.albert@shell.com

Lease(s): G 8496 Area: MC Block(s): 657 Project Name (If Applicable): Coulomb

Objective(s): X Oil Gas Sulphur Salt Onshore Base: Fourchon and Amelia Distance to Closest Land (Miles): 84

Description of Proposed Activities (Mark all that apply)

Exploration drilling X Development drilling

X 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

X Installation of subsea wellheads and/or manifolds X Commence production

Installation of lease term pipelines Other (Specify and describe) Pipeline appurtenance

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

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

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

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

Have all of the surface locations of your proposed activities been previously reviewed and approved by BOEM? Yes X No

*CID will be submitted if requested by Regional Supervisor per 30 CFR 550.296(a).

Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

See attached

Description of Drilling Rig Description of Production Platform

Jackup X Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Compliant tower

Semisubmersible X Submersible Fixed platform Guyed tower

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

Drilling Rig Name (If Known): Transocean Nautilus or similar

 Noble Don Taylor or similar

Noble Jim Day or similar

Spar Other (Attach Description)

Description of Lease Term Pipelines

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

See attached

Form BOEM-0137 (December 2011-Supercedes all previous editions of form BOEM-0137 which may not be used.) 

 

Page 14 Public Information Copy
Attachment 1C.1 

Installation Schedule & Lease Term Pipelines 

Proposed Activity Start Date End Date No. of Days

Drill and complete well C-4 2/1/2015 7/06/2015 155

Jumper & umbilical installation 7/7/2015 8/7/2015 31

Manifold Installation 8/7/2015 8/8/2015 1

Commence production for well C-4 8/9/2015

Drill and complete well C-5 2/1/2016 7/5/2016 155

Jumper installation & umbilical installation 7/6/2016 7/30/2016 24

Commence production Well C-5 7/31/2016

Description of Lease Term Pipelines

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

Production Flowline Inline Sled (MC 657) C-4 Subsea Tree (MC 657) 6.625” OD 75’

Truss Jumper – C-3 side (MC 657) Production Flowline End 

Termination (MC 657)

8.625” OD 82’

Truss Jumper – C-2 side (MC 657) Truss Jumper – C-3 side (MC 657) 8.625” OD 131’

Truss Jumper – C-2 side (MC 657) CG-1 Sled 8.625” OD 82’

C-2 Subsea Tree (MC 657) Truss Jumper – C-2 side (MC 657) 6.625” OD 60’

Page 15 Public Information Copy
 

Attachment 1D

OCS PLAN INFORMATION FORM (CONTINUED) 

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

Proposed Well/Structure Location

Well or Structure Name/Number (If renaming well or structure, reference previous name): C-4 Subsea Completion

Anchor Radius (if applicable) in feet: 15,000’ X Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 8496

Area Name Mississippi Canyon

Block No. 657

Blockline

Departures

(in feet)

N/S Departure: 317’ FNL

E/W Departure 4,213’ FEL

Lambert X-Y 

coordinates

X: 1,342,187’

Y: 10,295,683’

Latitude/

Longitude

Latitude 28.3678679

Longitude -87.9276436

TVD (Feet): MD (Feet): Water Depth (Feet): 7,553’

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor Chain on 

Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. 2501 et seq.) requires us to inform you that 

BOEM collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document submitted for 

BOEM approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the 

Freedom of Information Act and 30 CFR 550.197. An agency may not conduct or sponsor, and a person is not required to respond to, a collection 

of information unless it displays a currently valid Office of Management and Budget Control Number. Responses are mandatory (43 U.S.C. 1334). 

The public reporting burden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordination 

Documents. We estimate that burden to average 600 hours with an accompanying EP, or 700 hours with an accompanying DPP or DOCD, 

including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the forms associated with subpart 

B. Direct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Bureau of 

Ocean Energy Management, 381 Elden Street, Herndon, VA 20170.

Form BOEM-0137 (December 2011-Supercedes all previous editions of form BOEM-0137 which may not be used.)

Page 16 Public Information Copy
Attachment 1E 

OCS PLAN INFORMATION FORM (CONTINUED) 

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

Proposed Well/Structure Location

Well or Structure Name/Number (If renaming well or structure, reference previous name): C-5 Subsea Completion

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

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 8496

Area Name Mississippi Canyon

Block No. 657

Blockline

Departures

(in feet)

N/S Departure: 310’ FNL

E/W Departure 4,220’ FEL

Lambert X-Y 

coordinates

X: 1,342,180’

Y: 10,295,690’

Latitude/

Longitude

Latitude 28.3678870

Longitude -87.9276655

TVD (Feet): MD (Feet): Water Depth (Feet): 7,553’

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

Anchor Name

or No.

Area Block X Coordinate Y Coordinate Length of Anchor Chain on 

Seafloor

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. 2501 et seq.) requires us to inform you that 

BOEM collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document submitted for 

BOEM approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the 

Freedom of Information Act and 30 CFR 550.197. An agency may not conduct or sponsor, and a person is not required to respond to, a collection 

of information unless it displays a currently valid Office of Management and Budget Control Number. Responses are mandatory (43 U.S.C. 1334). 

The public reporting burden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordination 

Documents. We estimate that burden to average 600 hours with an accompanying EP, or 700 hours with an accompanying DPP or DOCD,

including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the forms associated with subpart 

B. Direct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Bureau of 

Ocean Energy Management, 381 Elden Street, Herndon, VA 20170.

Form BOEM-0137 (December 2011-Supercedes all previous editions of form BOEM-0137 which may not be used.)

Page 17 Public Information Copy
Attachment 1F - Coulomb Subsea Field Layout

Page 18 Public Information Copy
SECTION 2: GENERAL INFORMATION 

A. Application and Permits 

Application/Permit Issuing Agency Status

Rig Movement Report USCG, MWA & NGA Pending

Military Warning Area Agreement USAF Pending

Application for permit to drill BSEE Pending

B. Drilling Fluids 

See Section 7, Tables 7A and 7B for this information. 

C. Production 

Type Average Production Rate

Peak Production 

Rate

Life of 

Reservoir

Oil 5,700 BOPD 14,200 BOPD 28 Years

Gas 21.6 MMSCFD 49.5 MMSCFD 28 Years

D. Oil Characteristics 

The BS50 South hydrocarbons characteristics assumed for the reservoir fluids were based on the 1) 

downhole MDT samples from exploration wells (year 2000); 2) surface recombined samples taken very 

early in the field life (year 2004); 3) surface recombined samples obtained 2 years after first oil (year 

2006). Batch-one downhole samples have very high mud contamination so they are not suitable for PVT 

analysis. Batch-three have no contamination, but they came in 2 years after production started. 

Therefore, the surface recombined samples from batch-two were used for PVT analysis and the EOS 

modeling afterwards. C-2 gas sample cannot be used as the “average” gas composition because it was 

collected from the crest of the structure. Hence, a small modification was performed on the sample 

composition to create a “representative” gas composition for the entire structure. The modified C 2 gas 

composition can be found in below table with the summary of compositions of BS50 South gas and oil 

rim. Exploration well ST1 intersected possible oil rim; however, no oil samples could be collected in two 

RFT sample runs (only gas and mud filtrate), and hence large uncertainty is expected in oil compositions, 

oil type, and other relevant data. In this work, the compositional gradient module in the pvt simulator 

(PVTSim) was used to “generate” oil compositions below the original gas oil contact based on the 

Coulomb gas sample depth, reservoir pressure at the sample depth, as well as the temperature gradient. 

During the dynamic work the gradient black oil composition were used in simulation models for the design 

assumption and their basic bulk properties are shown below. These compositions had been used for the 

dynamic simulation models. 

Page 19 Public Information Copy
Note: Actual fluid properties will be determined once the oil rim is proved and the laboratory analysis are 

performed. 

The reservoir H2S content is 0.0 % as determined in the C-2 fluid sample “Gas Condensate Full PVT Study 

Report” performed in June 2004.

Analytical Methodologies

Should Be Compatible With:

1. Gravity (API) 46 ASTM D4052

2. Flash Point (oC Condensate ASTM D93/IP 34

3. Pour Point (oC) Condensate ASTM D97

4. Viscosity (Centipoise at 25 oC) 1.17 ASTM D445

5. Wax Content (wt %) Precipitate with 2-butanon/dichloromethane

(1 to 1 volume) at -10 oC

6. Asphaltene Content (wt %) IP-Method 143/84

7. Resin Content (wt %) Jokuty et al., 1996

8. Boiling point distribution including, for each

fraction, the percent volume or weight and 

the

boiling point range in oC

ASTM D2892 (TBP distillation) or

ASTM D2887/5307

9. Sulphur (wt %) 0 ASTM D4294

Note: If the distillation information in Item No. 8 in the above table is not available, the GOMR may accept 

the following information in lieu of Items Nos. 5, 6, 7, and 8: weight percent total of saturates, aromatics, 

waxes, asphaltenes, and resins; and total BTEX (ppm) using analytical methods compatible with the 

Hydrocarbon Groups methodology found in Jokuty et al. 

Identify the oil you analyze. Refer to the following sample chart. 

*Oil from one well Oil from more than one 

well sampled on a facility Oil from a pipeline system

·Area/Block 

·MMS platform 

·API Well No. 

·Completion perforation

 interval 

·BOEM’s reservoir name

·Sample date 

·Sample No.(if more than one 

is taken) 

·Area/Block

·BSEE platform ID 

·Field/Unit 

·Sample date 

·Sample No. (if more than one 

is taken)

·Listing of API Well Nos.

·Storage tank ID No. (if 

sampled at a storage tank)

·Pipeline segment number

·For each pipeline that feeds 

into the system, the ID codes 

for the closest upstream LACT 

units and/or facility 

measurement points

·Storage tank ID No. (if 

sampled at a storage tank)

*Sample Detail 

Area/Block MC 657

BSEE Platform Subsea C-2 

API Well No. 608174087203

Completion Perforation 17,158-17,276

BOEM Reservoir Name MUM F2

Sample Date 2006

Page 20 Public Information Copy
E. New Or Unusual Technology 

There is no new or unusual technology associated with this plan. 

 

F. Bonding 

The bond requirement for the activities proposed in this DOCD 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 additional security under 30 CFR 256.53(d) and National NTL No. 

2008-N07, “Supplemental Bond Procures.”

G. Oil Spill Financial Responsibility (OSFR) 

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

responsibility for the facilities proposed in the DOCD according to 30 CFR part 253, and NTL No. 2008-

N05, “Guidelines for Oil Spill Financial Responsibility for Covered Facilities.”

H. Deepwater well control statement 

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

and conduct other emergency well control operations. 

I. Suspension of Production 

This lease is not under a Suspension of Production. 

Page 21 Public Information Copy
J. Blowout scenario 

Summary 

This Section 2J was prepared by Shell pursuant to the guidance provided in the BOEM’s NTL 2010-N06 with 

respect to blowout and worst case discharge scenario descriptions. 

Shell is a founding member of the Marine Well Containment Company (MWCC) and will have access to an 

integrated subsea well control and containment system that can be rapidly deployed through the MWCC. 

MWCC is a non-profit Shell focuses on an integrated, three-pronged approach to a blowout, including 

prevention, intervention/containment and recovery. Shell believes that the best way to manage blowouts is 

to prevent them from happening. Significant effort goes into the design and execution of wells and into 

building and maintaining staff competence with the goal of safe and environmentally sound well construction. 

Shell continues to invest independently in research and development to improve safety and reliability of our 

well systems. We are actively complying with all applicable laws, regulations, rules and Notice to Lessees. 

Shell is investing in R&D to improve containment systems. As outlined in Shell’s Regional OSRP and detailed 

in EP Section 9a (ii), Shell has contracts with ORSOs to provide the resources necessary to respond to this 

WCD scenario. 

The Worst Case Discharge (WCD) blowout scenario for Coulomb is calculated for the MC657 C-4 with all 

potentially producible hydrocarbons sands based on the guidelines outlined in NTL No. 2010-N06 along with 

subsequent Frequently Asked Questions (FAQ). In the unlikely event of a spill, Shell’s Regional OSRP (April 

2013) is designed to contain and respond to a spill that meets or exceeds this WCD. The WCD does not take 

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

barriers, or early intervention. See Table 2.1 below. 

Uncontrolled blowout (volume first day) 49,711 bbl

Uncontrolled blowout rate (first 30-days average daily rate) 15,000 bopd

Duration of flow (days) based on relief well 101 days

Total volume of spill (bbls) for 101 days 1.564 MMBO

Table 2.1 Worst Case Discharge Summary 

The Coulomb field is a subsea development in the deepwater Gulf of Mexico that will be tied back to the Na 

Kika platform via two 8” flow lines. Coulomb is located on a unit approximately 26 miles southeast of the Na 

Kika platform. The subsea system is located in approximately 7,570 feet of water. 

The Coulomb Phase 2 Field Redevelopment is the second phase of an existing subsea tieback to the Na Kika 

Platform in Mississippi Canyon Block 474. The planned redevelopment of the Coulomb field includes new 

subsea infrastructure, a new flowline back to Na Kika with riser base gas lift (RBGL) including the gas lift SCR, 

a new umbilical to the drill center, a new C-4 well, and topsides modifications. The Coulomb field was first 

developed with the Na Kika project and included two wells, (C-2 and C-3), a single flowline, umbilical, and 

associated topsides equipment. First oil will be accomplished with unload of C-4 through the new flowline. 

C-5 is a back-up well location. 

Page 22 Public Information Copy
1) Purpose 

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

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

calculations used to determine the WCD and the measures taken to firstly enhance the ability to prevent a 

blowout and secondly to respond and manage a blowout scenario if it were to occur. These calculations are 

based on best technical estimates of subsurface parameters that are derived from the Coulomb development 

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 

The information in this section of the plan has been developed to document the additional information 

requirements for EPs as requested by NTL No. 2010-N06 in response to the explosion and sinking of the 

Mobile Offshore Drilling Unit (MODU) Deepwater Horizon. 

3) Information Requirements 

a) Blowout scenario 

The MC657 C-4 well trajectory penetrates the target sands and is cased with liner and cemented; 

hence three blowout scenarios were considered. First was the uncontrolled blowout from the sand 

through the openhole to the casing. The second scenario was an uncontrolled blowout from the 

sand, through openhole, through the cemented liner, and through casing. The third uncontrolled 

blowout scenario was from the target sand through casing and tieback. The three simulated blowout 

scenarios modeled result in unrestricted flow from the sands to well at the seafloor, which represents 

the WCD (no restrictions in wellbore, failure/loss of the subsea BOP, and a blowout to the seabed). 

The flow from the target sand scenario represents the highest flow potential. 

The worst case discharge is identified to be in the target sand through the open hole section, through 

the casing. The WCD rate is 49,711 BBL/D; this occurs on day one following the uncontrolled 

blowout. The table 2.2 shows the WCD Scenario that occurs on day one and Table 2.3 shows WCD 

on day 101. 

b) Estimated flow rate of the potential blowout 

Category EP

Type of Activity Drilling 

Facility Location (area/block) MC-657 

Facility Designation MODU 

Distance to Nearest Shoreline (miles) 84 Statute miles

Uncontrolled blowout (volume first day) 49,711 bbl 

Uncontrolled blowout rate (first 30-days average daily rate) 15,000 bopd 

Table 2.2 Estimated Flow Rates of a Potential Blowout 

Page 23 Public Information Copy
c) Total volume and maximum duration of the potential blowout 

Duration of flow (days) 101 days total duration to drill relief well 

(17 days rig mob, 54 days spud to base of sand, 30 days precision 

ranging). 

Total volume of spill (bbls) 1.126 MMBO based on 101 days flowing. 

Note: From GAP/MBAL/PROPSER model 

Table 2.3 Estimated Duration and Volume of a Potential Blowout 

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

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 a well first starts flowing to a 

pseudo-steady state pressure profile with time, and, as a result, the rate declines. At somewhat longer 

time scales, effects such as reservoir voidage and the impact of boundaries can cause the rate to drop 

continuously with production. Simulation and material balance models can include these effects and form 

the basis of the NTL No. 2010-N06 estimates for 24-hour and 30-day rates as well as maximum duration 

volumes. 

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

Page 24 Public Information Copy
SECTION 3: GEOLOGICAL AND GEOPHYSICAL INFORMATION 

A. Geological description 

Proprietary data 

B. Structure Contour Map(s) 

Proprietary data 

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

Proprietary data

D. Geological Structure Cross-section(s) 

Proprietary data

E. Shallow Hazards Report 

McClelland Engineers, Shallow Hazards Report, Blocks 612, 613, 656, and 657, Mississippi Canyon 

Area, Gulf of Mexico, Project No. 0186-2068, dated December 18, 1986. Data includes: Sparker, 

Deep tow side-scan sonar and sub-bottom profiler. (C targets) 

GEMS, Inc., Geologic and Stratigraphic Assessment, Block 701 (OCS G-21183) Mississippi Canyon 

Area, Gulf of Mexico, Project No. 0605-1004, dated October 10, 2005. Data includes: 3-D Seismic 

and Deep-tow side-scan sonar and sub-bottom profiler. (SC targets) 

C&C Technologies. AUV Hazard Study, Blocks 657 (OCS-G-09496), 701 (OCS-G-21183), Mississippi 

Canyon Area, and 617 (CS-G-23525) and 661 (Unleased), Desoto Canyon Area, Project No. 061829, 

dated January 2007. Data includes: AUV side-scan sonar and sub-bottom profiler. (DC617-2006 

targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 

617 (Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. 

Data includes: 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 targets) 

Page 25 Public Information Copy
Archaeological Report and Data 

Marmaduke & Assoc, LLS. Cultural Resource Evaluation, Mississippi Canyon Blocks 612, 613, 656, 

657, & 701, dated August 2005. Data includes: Deep-tow side-scan sonar and sub-bottom profiler. 

(C targets) 

C&C Technologies. Archaeological Assessment “Shallow Coulomb” Prospect, Blocks 657 (OCS-G09496), 701 (OCS-G-21183), Mississippi Canyon Area, and 617 (CS-G-23525), and 661 (Unleased), 

Desoto Canyon Area, Project No. 061829, dated December 2006. Data includes: AUV side-scan 

sonar and sub-bottom profiler. (DC617-2006 targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 

617 (Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. 

Data includes: Re-processed 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 

targets) (This report is being provided with this Plan.) 

GEMS, Inc. Geologic, Stratigraphic, and Archaeological Assessment of Block 566 (OCS-G 8831), 567 

(OCS-G 33744), 611 (OCS-G 27287) 612 (OCS-G 33166) and 656 (OCS-G 33752), Mississippi Canyon 

Area, Gulf of Mexico, Project Number 0811-1984a, August 22, 2012. 

F. Shallow Hazards Assessment 

See Section 6 for full shallow hazards and chemo assessment. 

G. High-resolution seismic lines 

Proprietary data. ESR can be found in Section 6. 

H. Stratigraphic Column and Time versus Depth Table: 

Proprietary data

Page 26 Public Information Copy
SECTION 4: HYDROGEN SULFIDE (H2S) 

A. Concentration 

0 ppm. 

B. Classification

Based on 30 CFR 550.215, Shell requests that the Regional Supervisor, Field Operations, determine 

the zones in the proposed drilling operations in this plan are classified as an area where the absence 

of H2S has been confirmed. 

C. H2S Contingency Plan 

According to NTL 2008-G04 this is not applicable to this plan. 

D. Modeling Report 

We do not anticipate to encounter or handle H2S at concentrations greater than 500 parts per million 

(ppm) and therefore have not included modeling for H2S.

Page 27 Public Information Copy
SECTION 5: MINERAL RESOURCE CONSERVATION INFORMATION 

A. Technology and reservoir engineering practices and procedures 

 Proprietary data 

B. Technology and recovery practices and procedures 

 Proprietary data 

 

C. Reservoir Development 

Proprietary data 

Page 28 Public Information Copy
SECTION 6: BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION 

A. Shallow Hazards Reports and Data: 

McClelland Engineers, Shallow Hazards Report, Blocks 612, 613, 656, and 657, Mississippi Canyon 

Area, Gulf of Mexico, Project No. 0186-2068, dated December 18, 1986. Data includes: Sparker, 

Deep tow side-scan sonar and sub-bottom profiler. (C targets) 

GEMS, Inc., Geologic and Stratigraphic Assessment, Block 701 (OCS G-21183) Mississippi Canyon 

Area, Gulf of Mexico, Project No. 0605-1004, dated October 10, 2005. Data includes: 3-D Seismic 

and Deep-tow side-scan sonar and sub-bottom profiler. (SC targets) 

C&C Technologies. AUV Hazard Study, Blocks 657 (OCS-G-09496), 701 (OCS-G-21183), Mississippi 

Canyon Area, and 617 (CS-G-23525) and 661 (Unleased), Desoto Canyon Area, Project No. 061829, 

dated January 2007. Data includes: AUV side-scan sonar and sub-bottom profiler. (DC617-2006 

targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 

617 (Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. 

Data includes: 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 targets) 

Archaeological Report and Data: 

Marmaduke & Assoc, LLS. Cultural Resource Evaluation, Mississippi Canyon Blocks 612, 613, 656, 

657, & 701, dated August 2005. Data includes: Deep-tow side-scan sonar and sub-bottom profiler. 

(C targets) 

C&C Technologies. Archaeological Assessment “Shallow Coulomb” Prospect, Blocks 657 (OCS-G09496), 701 (OCS-G-21183), Mississippi Canyon Area, and 617 (CS-G-23525), and 661 (Unleased), 

Desoto Canyon Area, Project No. 061829, dated December 2006. Data includes: AUV side-scan 

sonar and sub-bottom profiler. (DC617-2006 targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 

617 (Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. 

Data includes: Re-processed 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 

targets) 

Proposed Locations and Coordinates 

Proposed Location

MC 657

X

Coordinate

Y

Coordinate

Lease Calls

FNL/FSL

Lease Calls

FEL/FWL Water Depth

Prop Loc C-4 1,342,187 10,295,683 317’ FNL 4213’ FEL 7553’

Prop Loc C-5 1,342,180 10,295,690 310’ FNL 4220’ FEL 7553’

Coordinates are in UTM 316, NAD27 

Site Assessment, MC 657, Proposed Location C-4:

Mississippi Canyon 657, Proposed Location C-4 is located in a water depth of approximately 7553 feet 

and will be located within Military Warning Area EWTA-1.

Proposed Location C-4 will be positioned 2185’ northwest of Shell’s previously drilled MC657 C-3 

location, 2198’ northwest of Shell’s previously drilled MC657 C-2 location, and 4950’ north-northeast 

of Shells’ previously drilled MC 657-1 location and will not interfere with any of these previously 

drilled locations. 

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

features within 2000’ of Proposed Location C-4. 

Page 29 Public Information Copy
The stratigraphy at the site of MC 657, Proposed Location C-4 consists of: 

 Unit 1 Blue Unit - (Seafloor – 261’ BML) 69’ of hemipelagic drape overlying 96’ MTD’s

Unit 2 (261’ – 971’ BML) 710’ of low amplitude, continuous reflectors indicative of muddy 

sediments 

Unit 3 (971’ – 2091’ BML) 1120’of low amplitude, continuous moderate amplitude, 

discontinuous reflectors, indicative of muddy sediments in the upper half and mud with silts and 

sands in lower half 

Unit 4 (2091’ – 3257’ BML) 1166’ of moderate amplitude, discontinuous to chaotic reflectors 

indicative of a channel complex consisting of muds and sands 

Unit 5 (3257’ – 3767’ BML) 510’ of low to moderate amplitude, discontinuous reflectors 

indicative of a mass failure system consisting of sands and muds 

Shallow Water Flow Potential: 

 Low - Seafloor – 2091’ BML

 Moderately – 2091’ – 3257’ BML

 Low – 3257’ 3767’ BML

Shallow Gas Potential 

 Low – Seafloor – 3767’ BML

Buried high-amplitudes anomalies are identified within the following units: 

Unit 3 (971’ – 2091’ BML) 750’ to North

Unit 4 (2091’ – 3257’ BML) 400’ to North

MC 657, Proposed Location C-4 will not penetrate these buried amplitude anomalies. 

Benthic/Anchor Assessment, MC 657, Proposed Location C-4, (15,000’ generic anchor 

radius) 

Mississippi Canyon 657, Proposed Location C-4 is located in a water depth of approximately 7553 

feet. There is no evidence of seafloor or near-surface slumping, faulting, amplitude or fluid expulsion 

features within the 15000’ generic anchor radius of this location and this location will not disturb any 

high-density areas of benthic communities. 

 

No marine avoidance zones are identified within 2000’ of this location. 

The following table is a list of marine avoidance zones identified within 15,000’ proposed anchor 

radius for MC 657, Proposed Location C-4:

Avoidance 

Zone Number Avoidance 

Central X

Coordinate

Central Y 

Coordinate

Distance from 

Prop Loc C-4

Direction from 

Prop Loc C-4

C5 100’ 1,345,575.00 10,293,125.00 4245.22’ Southeast

C9 100’ 1,338,110.00 10,296,950.00 4269.33’ Northeast

C6 100’ 1,337,585.00 10,295,800.00 4603.49’ Northeast

C7 100’ 1,337,335.00 10,295,825.00 4854.08’ Northeast

DC573-2013-

70

100’ 1,347,464.37 10,294,816.14 5348.09’ Southeast

DC573-2013-

68

100’ 1,347,549.82 10,295,105.43 5393.83’ Southeast 

DC573-2013-

69

100’ 1,347,596.21 10,295,143.17 5436.08’ Southeast

DC573-2013-

76

100’ 1,346,920.39 10,292,646.16 5623.82’ Southeast

DC573-2013-

66

100’ 1,347,916.32 10,295,819.16 5730.94’ Northeast

DC573-2013-

60

100’ 1,348,018.28 10,296,288.99 5862.68’ Northeast

DC573-2013-

71

100’ 1,347,841.01 10,294,129.19 5863.63’ Southeast

Page 30 Public Information Copy
DC573

-2013-

78

100’ 1,347,065.08 10,292,296.52 5938.34’ Southeast

C8 100’ 1,335,910.00 10,295,975.00 6283.79’ Northeast

SC3 100’ 1,341,122.00 10,288,248.00 7510.89’ Southeast

DC573-2013-

43

100’ 1,348,068.39 10,3,00,464.21 7579.63’ Northeast

DC573-2013-

73

100’ 1,349,629.80 10,293,906.52 7651.87’ Southeast

DC573-2013-

41

100’ 1,348,000.34 10,300,674.22 7662.06’ Northeast 

SC4 100’ 1,344,706.00 10,288,279.00 7820.78’ Southeast

DC573-2013-

47

100’ 1,348,801.52 10,299,863.90 7825.08’ Northeast 

DC573-2013-

79

100’ 1,349,262.37 10,291,748.66 8095.67’ Southeast

DC573-2013-

38

100’ 1,348,274.23 10,301,083.58 8137.61’ Northeast

DC573-2013-

46

100’ 1,349,541.17 10,299,994.27 8524.72’ Northeast

C1 2000’ 1,341,450.00 10,287,125.00 8589.68’ Southeast

SC2 100’ 1,339,634.00 10,287,399.00 8668.48’ Southeast 

SC7 100’ 1,340,261.00 10,287,073.00 8822.79’ Southeast 

SC8 100’ 1,340,113.00 10,287,105.00 8825.17’ Southeast

SC6 2000’ 1,341,328.00 10,286,874.00 8850.78’ Southeast

SC12 100’ 1,343,335.00 10,286,600.00 9155.26’ Southeast

DC573-2013-

86

100’ 1,347,870.66 10,288,414.04 9227.23’ Southeast

DC573-2013-

85

100’ 1,349,690.45 10,289,888.89 9480.16’ Southeast

DC573-2013-

44

100’ 1,350,793.53 10,300,185.42 9713.09’ Northeast

DC573-2013-

36

100’ 1,349,519.93 10,302,136.19 9768.09’ Northeast 

DC573-2013-

37

100’ 1,349,762.03 10,301,918.49 9811.34’ Northeast 

SC13 100’ 1,339,466.00 10,285,957.00 10099.45’ Southeast

DC573-2013-

61

100’ 1,352,417.82 10,296,377.56 10254.37’ Northeast

DC617-2006-5 

and SC5 100’ 1,348,972.00 10,287,838.00 10372.09’ Southeast

DC573-2013-

91

100’ 1,348,984.13 10,287,837.03 10380.76’ Southeast 

DC573-2013-

93

100’ 1,348,481.05 10,287,359.67 10435.18’ Southeast 

DC573-2013-

87

100’ 1,349,701.31 10,288,427.10 10445.71’ Southeast 

DC573-2013-

42

100’ 1,351,724.06 10,300,632.71 10745.01’ Northeast 

SC1 100’ 1,334,275.00 10,288,261.00 10848.31’ Southeast 

DC573-2013-

45

100’ 1,352,109.02 10,300,124.97 10870.95’ Northeast 

SC15 100’ 1,345,143.00 10,284,504.00 11563.22’ Southeast

DC573-2013-

75

100’ 1,353,545.91 10,293,457.27 11574.92’ Southeast 

DC617-2006-

11 and SC11 100’ 1,349,702.00 10,286,553.00 11825.06’ Southeast 

DC573-2013-

48

100’ 1,353,374.48 10,299,925.85 11965.01’ Northeast 

Page 31 Public Information Copy
DC573

-2013-

80

100’ 1,353,476.89 10,291,311.30 12106.75’ Southeast

DC573-2013-

22

100’ 1,348,729.69 10,305,926.14 12154.37’ Northeast

SC10 100’ 1,333,831.00 10,286,784.00 12207.17’ Southeast

DC573-2013-

77

100’ 1,354,051.91 10,292,698.29 12234.57’ Southeast

DC573-2013-

83

100’ 1,353,529.09 10,290,777.15 12357.60’ Southeast 

DC617-2006-

14

and SC14

100’ 1,348,769.00 10,285,142.00 12427.20’ Southeast 

SC9 100’ 1,332,964.00 10,287,170.00 12551.29’ Southeast

C2 and C3 100’ 1,343,450.00 10,282,960.00 12785.53’ Southeast 

SC16 100’ 1,344,540.00 10,282,780.00 13115.79’ Southeast 

DC573-2013-

89

100 1,353,169.98 10,288,242.48 13266.02’ Southeast

DC573-2013-

62

100’ 1,355,481.63 10,296,135.56 13302.33’ Northeast

C4 100’ 1,338,950.00 10,282,710.00 13370.75’ Southeast

DC573-2013-

63

100’ 1,356,060.11 10,296,127.50 13880.23’ Northeast

DC617-2006-

20, and SC20 100’ 1,345,998.00 10,282,273.00 13941.01’ Southeast

DC573-2013-

72

100’ 1,356,078.90 10,294,291.60 13961.41’ Southeast

DC917-2006-

19 and SC19 100’ 1,346,097.00 10,282,273.00 13968.40’ Southeast

DC573-2013-

55

100’ 1,356,088.98 10,297,092.53 13973.25’ Northeast

C12 100’ 1,328,135.00 10,294,475.00 14103.83’ Southeast 

DC573-2013-

14

100’ 1,348,242.85 10,308,549.27 14220.20’ Northeast

DC573-2013-

88

100’ 1,354,394.81 10,288,386.48 14222.16’ Southeast

DC573-2013-

56

100’ 1,356,349.20 10,297,002.40 14223.53’ Northeast

DC573-2013-

64

100’ 1,356,454.54 10,296,170.68 14275.87’ Northeast

DC573-2013-

28

100’ 1,353,618.71 10,304,452.83 14408.12’ Northeast

DC573-2013-

81

100’ 1,355,920.45 10,291,153.76 14461.04’ Southeast

DC573-2013-

13

100’ 1,347,778.56 10,309,055.98 14494.90’ Northeast

DC573-2013-

65

100’ 1,356,693.63 11,296,094.47 14512.46’ Northeast

SC17 100’ 1,334,760.00 10,283,131.00 14584.68’ Southeast

DC617-2006-

21 and SC21 100’ 1,346,384.00 10,281,636.00 14660.59’ Southeast

DC573-2013-

39

100’ 1,355,986.77 10,301,064.93 14812.12’ Northeast 

DC573-2013-

23

100’ 1,353,238.78 10,305,717.46 14927.57’ northeast

Page 32 Public Information Copy
The following table is a list of marine avoidance zones identified within the 1000’ buffer zone 

(between 15,000’ – 16000’) for proposed anchor radius for MC 657, Proposed Location C-4:

Avoidance 

Zone Number Avoidance 

Central X

Coordinate

Central Y 

Coordinate

Distance from 

Prop Loc C-4

Direction from 

Prop Loc C-4

DC573-2013-

58

100’ 1,357,561.45 10,296,481.16 15395.15’ Northeast

SC22 100’ 1,341,076.00 10,280,195.00 15527.80’ Southeast

DC573-2013-

90

100’ 1,355,658.74 10,287,921.12 15547.82’ Southeast 

SC-23 100’ 1,345,340.00 10,280,286.00 15716.52’ Southeast

DC573-2013-

31

100’ 1,356,259.06 10,303,102.60 15908.28’ Northeast 

DC573-2013-

25

100’ 1,354,976.36 10,305,246.72 15969.74’ Northeast 

DC573-2013-

59

100’ 1,358,146.45 10,296,339.90 15972.96’ Northeast 

Proposed Location C-4 will be positioned approximately 250 feet northeast of Shell’s Coulomb 

flowlines. Proposed Location C-4 will not interfere with this existing flowline. 

Conclusion: 

Based on high-resolution surveys consisting of AUV Side Scan Sonar, and Sub-bottom Profiler, Air 

Gun data, Sparker, frequency enhanced 3-D Seismic, Enhanced Surface renderings (ESR’s), ESR’s 

with amplitudes applied, MC 657, Proposed Location C-4 appears suitable for the planned activity. 

Site Assessment, MC 657, Proposed Location C-5:

Mississippi Canyon 657, Proposed Location C-5 is located in a water depth of approximately 7553 

feet. 

Proposed Location C-5 is located within Military Warning Area EWTA-1.

Proposed Location C-5 will be positioned 2195’ northwest of Shell’s previously drilled MC657 C-3 

location, 2208’ northwest of Shell’s previously drilled MC657 C-2 location, and 4953’ north-northeast 

of Shells’ previously drilled MC 657-1 location. Proposed Location MC657 C-5 will not interfere with 

any of these previously drilled locations. 

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

features within 2000’ of Proposed Location C-5. 

The stratigraphy at the site of MC 765, Proposed Location C-5 consists of: 

 Unit 1 Blue Unit - (Seafloor – 261’ BML) 69’ of hemipelagic drape overlying 96’ MTD’s

Unit 2 (261’ – 971’ BML) 710’ of low amplitude, continuous reflectors indicative of muddy 

sediments 

Unit 3 (971’ – 2091’ BML) 1120’of low amplitude, continuous moderate amplitude, 

discontinuous reflectors, indicative of muddy sediments in the upper half and mud with silts and 

sands in lower half 

Unit 4 (2091’ – 3257’ BML) 1166’ of moderate amplitude, discontinuous to chaotic reflectors 

indicative of a channel complex consisting of muds and sands 

Unit 5 (3257’ – 3767’ BML) 510’ of low to moderate amplitude, discontinuous reflectors 

indicative of a mass failure system consisting of sands and muds 

Shallow Water Flow Potential: 

 Low - Seafloor – 2091’ BML 

 Moderately – 2091’ – 3257’ BML

 Low – 3257’ 3767’ BML

Page 33 Public Information Copy
Shallow Gas Potential 

 Low – Seafloor – 3767’ BML

Buried high-amplitudes anomalies are identified within the following units: 

Unit 3 (971’ – 2091’ BML) 750’ to North

Unit 4 (2091’ – 3257’ BML) 400’ to North

MC 657, Proposed Location C-5 will not penetrate these buried amplitude anomalies. 

Benthic/Anchor Assessment, MC 657, Proposed Location C-5, (15,000’ generic anchor 

radius) 

Mississippi Canyon 657, Proposed Location C-5 is located in a water depth of approximately 7553 

feet. 

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

features within the 15000’ generic anchor radius for Proposed Location C-5. MC 657, Proposed 

Location C-5 will not disturb any high-density areas of benthic communities. 

No marine avoidance zones are identified within 2000’ of MC 657, Proposed Location C-5.

The following table is a list of marine avoidance zones identified within 15,000’ proposed anchor 

radius for MC 657, Proposed Location C-5:

Avoidance 

Zone Number Avoidance 

Central X

Coordinate

Central Y 

Coordinate

Distance from 

Prop Loc C-5

Direction from 

Prop Loc C-5

C5 100’ 1,345,575.00 10,293,125.00 4255.03’ Southeast

C9 100’ 1,338,110.00 10,296,950.00 4260.58’ Northeast

C6 100’ 1,337,585.00 10,295,800.00 4596.32’ Northeast

C7 100’ 1,337,335.00 10,295,825.00 4846.88’ Northeast

DC573-2013-

70

100’ 1,347,464.37 10,294,816.14 5356.14’ Southeast

DC573-2013-

68

100’ 1,347,549.82 10,295,105.43 5401.55’ Southeast 

DC573-2013-

69

100’ 1,347,596.21 10,295,143.17 5443.74’ Southeast

DC573-2013-

76

100’ 1,346,920.39 10,292,646.16 5633.49’ Southeast

DC573-2013-

66

100’ 1,347,916.32 10,295,819.16 5737.77’ Northeast

DC573-2013-

60

100’ 1,348,018.28 10,296,288.99 5868.93’ Northeast

DC573-2013-

71

100’ 1,347,841.01 10,294,129.19 5872.24’ Southeast

DC573-2013-

78

100’ 1,347,065.08 10,292,296.52 5948.08’ Southeast

C8 100’ 1,335,910.00 10,295,975.00 6276.47’ Northeast

SC3 100’ 1,341,122.00 10,288,248.00 7516.83’ Southeast

DC573-2013-

43

100’ 1,348,068.39 10,3,00,464.21 7580.65’ Northeast

DC573-2013-

73

100’ 1,349,629.80 10,293,906.52 7660.31’ Southeast

DC573-2013-

41

100’ 1,348,000.34 10,300,674.22 7662.82’ Northeast 

DC573-2013-

47

100’ 1,348,801.52 10,299,863.90 7827.26’ Northeast 

SC4 100’ 1,344,706.00 10,288,279.00 7829.66’ Southeast

DC573-2013- 100’ 1,349,262.37 10,291,748.66 8105.19’ Southeast

Page 34 Public Information Copy
79

DC573-2013-

38

100’ 1,348,274.23 10,301,083.58 8138.20’ Northeast

DC573-2013-

46

100’ 1,349,541.17 10,299,994.27 8527.22’ Northeast

C1 2000’ 1,341,450.00 10,287,125.00 8596.05’ Southeast

SC2 100’ 1,339,634.00 10,287,399.00 8673.11’ Southeast 

SC7 100’ 1,340,261.00 10,287,073.00 8828.09’ Southeast 

SC8 100’ 1,340,113.00 10,287,105.00 8830.33’ Southeast

SC6 2000’ 1,341,328.0010,286,874.00 8857.07’ Southeast

SC12 100’ 1,343,335.00 10,286,600.00 9163.08’ Southeast

DC573-2013-

86

100’ 1,347,870.66 10,288,414.04 9237.06’ Southeast

DC573-2013-

85

100’ 1,349,690.45 10,289,888.89 9489.98’ Southeast

DC573-2013-

44

100’ 1,350,793.53 10,300,185.42 9716.05’ Northeast

DC573-2013-

36

100’ 1,349,519.93 10,302,136.19 9768.72’ Northeast 

DC573-2013-

37

100’ 1,349,762.03 10,301,918.49 9812.30’ Northeast 

SC13 100’ 1,339,466.00 10,285,957.00 10104.31’ Southeast

DC573-2013-

61

100’ 1,352,417.82 10,296,377.56 10260.88’ Northeast

DC617-2006-5 

and SC5 100’ 1,348,972.00 10,287,838.00 10381.96’ Southeast

DC573-2013-

91

100’ 1,348,984.13 10,287,837.03 10390.64’ Southeast 

DC573-2013-

93

100’ 1,348,481.05 10,287,359.67 10444.98’ Southeast 

DC573-2013-

87

100’ 1,349,701.31 10,288,427.10 10455.61’ Southeast 

DC573-2013-

42

100’ 1,351,724.06 10,300,632.71 10748.00’ Northeast 

SC1 100’ 1,334,275.00 10,288,261.00 10848.00’ Southeast 

DC573-2013-

45

100’ 1,352,109.02 10,300,124.97 10874.48’ Northeast 

SC15 100’ 1,345,143.00 10,284,504.00 11571.77’ Southeast

DC573-2013-

75

100’ 1,353,545.91 10,293,457.27 11583.13’ Southeast 

DC617-2006-

11 and SC11 100’ 1,349,702.00 10,286,553.00 11834.92’ Southeast 

DC573-2013-

48

100’ 1,353,374.48 10,299,925.85 11969.08’ Northeast 

DC573-2013-

80

100’ 1,353,476.89 10,291,311.30 12115.81’ Southeast

DC573-2013-

22

100’ 1,348,729.69 10,305,926.14 12152.24’ Northeast

SC10 100’ 1,333,831.00 10,286,784.00 12207.48’ Southeast

DC573-2013-

77

100’ 1,354,051.91 10,292,698.29 12243.06’ Southeast

DC573-2013-

83

100’ 1,353,529.09 10,290,777.15 12366.81’ Southeast 

DC617-2006-

14

And SC14

100’ 1,348,769.00 10,285,142.00 12436.85’ Southeast 

SC9 100’ 1,332,964.00 10,287,170.00 12550.90’ Southeast

C2 and C3 100’ 1,343,450.00 10,282,960.00 12793.19’ Southeast 

Page 35 Public Information Copy
SC16 100’ 1,343,450.00 10,282,960.00 13123.94’ Southeast 

DC573-2013-

89

100 1,353,169.98 10,288,242.48 13275.74’ Southeast

DC573-2013-

62

100’ 1,355,481.63 10,296,135.56 13309.09’ Northeast

C4 100’ 1,338,950.00 10,282,710.00 13375.85’ Southeast

DC573-2013-

63

100’ 1,356,060.11 10,296,127.50 13887.00’ Northeast

DC617-2006-

20, and SC20 100’ 1,345,998.00 10,282,273.00 13949.66’ Southeast

DC573-2013-

72

100’ 1,356,078.90 10,294,291.60 13969.07’ Southeast

DC917-2006-

19 and SC19 100’ 1,346,097.00 10,282,273.00 13977.08’ Southeast

DC573-2013-

55

100’ 1,356,088.98 10,297,092.53 13979.51’ Northeast

C12 100’ 1,328,135.00 10,294,475.00 14097.46’ Southeast 

DC573-2013-

14

100’ 1,348,242.85 10,308,549.27 14216.86’ Northeast

DC573-2013-

88

100’ 1,354,394.81 10,288,386.48 14229.85’ Southeast

DC573-2013-

56

100’ 1,356,349.20 10,297,002.40 14231.76’ Northeast

DC573-2013-

64

100’ 1,356,454.54 10,296,170.68 14282.63’ Northeast

DC573-2013-

28

100’ 1,353,618.71 10,304,452.83 14409.42’ Northeast

DC573-2013-

81

100’ 1,355,920.45 10,291,153.76 14469.88’ Southeast

DC573-2013-

13

100’ 1,347,778.56 10,309,055.98 14491.15’ Northeast

DC573-2013-

65

100’ 1,356,693.63 11,296,094.47 14519.26’ Northeast

SC17 100’ 1,334,760.00 10,283,131.00 14587.15’ Southeast

DC617-2006-

21 and SC21 100’ 1,346,384.00 10,281,636.00 14669.31’ Southeast

DC573-2013-

39

100’ 1,355,986.77 10,301,064.93 14816.10’ Northeast 

DC573-2013-

23

100’ 1,353,238.78 10,305,717.46 14928.05’ northeast

The following table is a list of marine avoidance zones identified within the 1000’ buffer zone 

(between 15,000’ – 16000’) for proposed anchor radius for MC 657, Proposed Location C-5:

Avoidance 

Zone Number Avoidance 

Central X

Coordinate

Central Y 

Coordinate

Distance from 

Prop Loc C-5

Direction from 

Prop Loc C-5

DC573-2013-

58

100’ 1,357,561.45 10,296,481.16 15401.78’ Northeast

SC22 100’ 1,341,076.00 10,280,195.00 15534.28’ Southeast

DC573-2013-

90

100’ 1,355,658.74 10,287,921.12 15557.38’ Southeast 

SC-23 100’ 1,345,340.00 10,280,286.00 15724.78’ Southeast

DC573-2013-

31

100’ 1,356,259.06 10,303,102.60 15911.21’ Northeast 

DC573-2013-

25

100’ 1,354,976.36 10,305,246.72 15971.15’ Northeast 

DC573-2013-

59

100’ 1,358,146.45 10,296,339.90 15979.67’ Northeast 

Page 36 Public Information Copy
Proposed Location C-5 will be positioned approximately 250 feet northeast of Shell’s Coulomb 

flowlines. Proposed Location C-5 will not interfere with this existing flowline. 

Conclusion: 

Based on high-resolution surveys consisting of AUV Side Scan Sonar, and Sub-bottom Profiler, Air Gun data, 

Sparker, frequency enhanced 3-D Seismic, Enhanced Surface renderings (ESR’s), ESR’s with amplitudes 

applied, MC 657, Proposed Location C-5 appears suitable for the planned activity. 

Proposed Seafloor Hardware, MC 657 

Proposed UTA-3, MC 657 

 X = 1,342,166.83 4233.17’ FEL

 Y = 10,295,782.70 217.30’ FNL

Mississippi Canyon 657, UTA-3 is located in a water depth of approximately 7553 feet. There is no evidence 

of seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion features within 2000’ of this area 

and will not disturb any high-density areas of benthic communities. There are no existing wells located within 

2000’ of MC 657, UTA-3.

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 300’ south of MC 657, Proposed UTA-3. MC 

657, UTA-3 will not interfere with any flowlines. No marine avoidance zones are identified within 2000’ of MC 

657, Proposed UTA-3.

Proposed EDM, MC 657 

 X = 1,342,222.93 3777.07’ FEL

 Y = 10,295,721.41 278.59’ FNL

Mississippi Canyon 657, EDM is located in a water depth of approximately 7553 feet. There is no evidence of 

seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion features within 2000’ of EDM. MC 

657, EDM will not disturb any high-density areas of benthic communities. There are no existing wells located 

within 2000’ of MC 657, EDM.

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 300’ south of MC 657, Proposed EDM. MC 

657, EDM will not interfere with any flowlines. No marine avoidance zones are identified within 2000’ of MC 

657, Proposed EDM. 

Proposed UTA-4, MC 657 

 X = 1,342,271.68 4128.32’ FEL

 Y = 10,295,678.27 321.73’ FNL

Mississippi Canyon 657, UTA-4 is located in a water depth of approximately 7553 feet. There is no evidence 

of seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion features within 2000’ of UTA-4. 

MC 657, UTA-4 will not disturb any high-density areas of benthic communities. 

There are no existing wells located within 2000’ of MC 657, UTA-4. Shell’s Coulomb PH1, 8” Gas Flowline is 

identified approximately 300’ south of MC 657, Proposed UTA-4. MC 657, UTA-4 will not interfere with any 

flowlines. No marine avoidance zones are identified within 2000’ of MC 657, Proposed UTA-4.

Page 37 Public Information Copy
Proposed Location C-4 In-Line Sled, MC 657 

 X = 1,342,130.20 4269.80’ FEL

 Y = 10,295,621.76 378.24’ FNL

Mississippi Canyon 657, Proposed Location C-4 In-Line Sled is located in a water depth of approximately 7553 

feet. There is no evidence of seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion 

features within 2000’ of Proposed Location C-4 In-Line Sled. MC 657, Proposed Location C-4 In-Line Sled will 

not disturb any high-density areas of benthic communities. There are no existing wells located within 2000’ 

of MC 657, Proposed Location C-4 In-Line Sled. 

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 160’ south of MC 657, Proposed Location C-4 

In-Line Sled. MC 657, Proposed Location C-4 In-Line Sled will not interfere with any flowlines. 

No marine avoidance zones are identified within 2000’ of MC 657, Proposed Location C-4 In-Line Sled. 

Proposed Location C-4 Alt-1 In-Line Sled, MC 657 

 X = 1,342,058.96 4341.04’ FEL

 Y = 10,295,691.97 308.03’ FNL

Mississippi Canyon 657, Proposed Location C-4 Alt-1 In-Line Sled is located in a water depth of approximately 

7553 feet. There is no evidence of seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion 

features within 2000’ of Proposed Location C-4 Alt-1 In-Line Sled. MC 657, Proposed Location C-4 Alt-1 InLine Sled will not disturb any high-density areas of benthic communities. There are no existing wells located 

within 2000’ of MC 657, Proposed Location C-4 Alt-1 In-Line Sled. 

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 243’ south of MC 657, Proposed Location C-4 

Alt-1 In-Line Sled. MC 657, Proposed Location C-4 Alt-1 In-Line Sled will not interfere with any flowlines. 

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 160’ south of MC 657, Proposed Location C-4 

Alt-1 In-Line Sled. MC 657, Proposed Location C-4 Alt-1 In-Line Sled will not interfere with any flowlines. 

No marine avoidance zones are identified within 2000’ of MC 657, Proposed Location C-4 Alt-1 In-Line Sled. 

Proposed Location C-4 Alt-2 In-Line Sled, MC 657 

 X = 1,342,023.34 4376.66’ FEL

 Y = 10,295,727.08 272.92’ FNL

Mississippi Canyon 657, Proposed Location C-4 Alt-2 In-Line Sled is located in a water depth of approximately 

7553 feet. There is no evidence of seafloor or near-surface slumping, faulting, amplitudes or fluid expulsion 

features within 2000’ of Proposed Location C-4 Alt-2 In-Line Sled. MC 657, Proposed Location C-4 Alt-2 InLine Sled will not disturb any high-density areas of benthic communities. There are no existing wells located 

within 2000’ of MC 657, Proposed Location C-4 Alt-2 In-Line Sled. 

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 243’ south of MC 657, Proposed Location C-4 

Alt-2 In-Line Sled. MC 657, Proposed Location C-4 Alt-2 In-Line Sled will not interfere with any flowlines. 

Shell’s Coulomb PH1, 8” Gas Flowline is identified approximately 160’ south of MC 657, Proposed Location C-4 

Alt-2 In-Line Sled. MC 657, Proposed Location C-4 Alt-2 In-Line Sled will not interfere with any flowlines. 

No marine avoidance zones are identified within 2000’ of MC 657, Proposed Location C-4 Alt-2 In-Line Sled. 

Conclusion: 

Based on a high-resolution geophysical survey consisting of frequency enhanced 3-D seismic, sparker, deeptowed side scan sonar and sub-bottom profiler, Enhanced Surface Renderings (ESR’s) and ESR’s with 

amplitudes applied, Mississippi Canyon 474 and 657 appear suitable for the planned activity. 

Page 38 Public Information Copy
Arch Reports: 

Archaeological Report (MC 612, 613, 656, 657, 701): 

Marmaduke & Assoc, LLS. Cultural Resource Evaluation, Mississippi Canyon Blocks 612, 613, 656, 657, & 

701, dated August 5, 2005. Data includes: Deep-tow side-scan sonar and sub-bottom profiler. 

Archaeological Conclusions and Recommendations (MC 612, 613, 656, 657, 701): 

Marmaduke & Associates, LLC recommends that Shell Offshore treat Sonar Target No. 5 as a possible 

significant shipwreck and immediately report it to the Minerals Management Service as a discovery. All 

operations, including even cursory inspection of the sea floor, should be suspended immediately within 600 

meters (1,969 feet) of the site, and should not be resumed until the Regional Director of the Minerals 

Management Service instructions Shell Offshore on what steps to take to assess the potential historical 

significance of the site, and on what measures must be taken to protect it should it be determined to be 

historically significant. Under no circumstances should Shell Offshore, Inc. or any of its contractors and 

consultants, disturb the materials at Target No. 5 without the knowledge and approval of the Regional 

Director. 

Other targets reported here – with the exception of the COMPATT transponders – are too small to be wrecks, 

probably, in their own right. The possibility cannot be dismissed, however, that one or more of these targets 

may be dispersed wreckage associated with the sinking of the possible vessel identified here as Target No. 5. 

All of these other targets should be treated, therefore, as contacts of possible archaeological significance and 

should be avoided by 200 meters (656 feet) unless ROV inspection proved them to be modern man-made 

objects or natural phenomena. Unfortunately nine of the targets have insufficiently accurate location 

information to make a reasonable avoidance recommendation. These targets, however, are located 

somewhere outside of the basic survey grid during the lead in and lead out of survey lines, along with line 

turns. 

Archaeological Report (MC 657, 701, DC 617, 661): 

C&C Technologies. Archaeological Assessment “Shallow Coulomb” Prospect, Blocks 657 (OCS-G-09496), 701 

(OCS-G-21183), Mississippi Canyon Area, and 617 (CS-G-23525), and 661 (Unleased), Desoto Canyon Area, 

Project No. 061829, dated December 2006. Data includes: AUV side-scan sonar and sub-bottom profiler. 

Archaeological Conclusions and Recommendations (MC 657, 701, DC 617, 661): 

Data assessment for this portion of the “Coulomb” Prospect located thirty-seven unidentified sonar contacts 

including thirty-five isolated targets, one debris zone, and a shipwreck. Thirty-one of the isolated finds are 

considered modern debris or geologic features and are not recommended for archaeological avoidance or 

investigation. Four of the isolated sonar contacts may represent outlying shipwreck debris. These contacts 

(Nos. 2, 3, 7 and 8) are within the wreck’s existing avoidance zone. No additional avoidances are 

recommended. If an ROV investigation of the wreck is conducted, these targets should be investigated to 

verify they are shipwreck debris. 

A single debris zone was noted in the survey area. The field is likely modern or geologic. This debris zone is 

not considered to have historic potential based on its acoustic signature and is not recommended for 

archaeological avoidance or investigation. 

A previously located shipwreck site was investigated during this survey. The wreck was originally located 

during 1986 deep-tow survey. The acoustic data was analyzed and compared to recently investigated 

deepwater shipwrecks in the Green Canyon and Viosca Knoll Areas. The analysis suggests the MC 657 

shipwreck is probably an historic wooden sailing vessel, possibly copper-clad, embedded up to six feet into 

the seafloor. The vessel’s lower hull may be intact beneath the bottom sediments. The hypothesis that the 

vessel is copper-clad is based on a comparison of the sonar reflectivity with several known copper-clad 

vessels (including the Petronius Wreck in the Viosca Knoll Area). High-resolution side scan sonar data of the 

Petronius Wreck is available and a recent ROV investigation confirmed that it is a wooden hull copper-clad 

Page 39 Public Information Copy
sailing vessel. Comparison of the side scan imagery shows distinct similarities in reflectivity between the 

Petronius Wreck and the MC 657 wreck. 

It is recommended that the 2,000-ft avoidance zone previously established by the Minerals Management 

Service be maintained. It is also suggested that if the opportunity occurs, a ROV survey of the wreck site be 

conducted under the supervision of a qualified marine archaeologist to determine its historical importance. 

It is possible another shipwreck exists undetected or unidentified within the survey area. If wood beams, 

planking, ceramics, or other possible cultural materials are encountered during lease development, the MMS 

archaeologists should be contacted within 48 hours for an assessment of any antiquities. In this event, no 

activities should be conducted near the area or discovery until advised by the appropriate personnel. 

Archaeological Report (DC 573): 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 617 

(Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. Data includes: 

re-processed 3-D seismic, AUV side-scan sonar and sub-bottom profiler. 

Archaeological Conclusions and Recommendations (DC573) 

None of the unidentified side-scan sonar contacts in the 2013 AUV Survey Area are recommended for 

archaeological avoidance or investigation; however, care should be taken when working near all of the 

unidentified side-scan sonar contacts to prevent potential damage or impact to development infrastructure. A 

standard 100-ft geohazard avoidance is recommended for these contacts. 

B-F: 

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

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

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

G. Remotely Operated Vehicle (ROV) Monitoring Plan

Mississippi Canyon Block 657 is located in Grid 17, which has inadequate ROV coverage so in accordance with 

the provisions of NTL No. 2008-G06, Remotely Operated Vehicle Surveys in Deepwater, we will perform preand post-ROV surveys unless otherwise directed by the Regional Supervisor. Shell is familiar with the survey 

and reporting provisions of the NTL and will comply with same. 

Page 40 Public Information Copy
H. Threatened and Endanger Species Information

There are 5 species of sea turtles that may be found in the 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 T

There are 28 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

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

Page 41 Public Information Copy
I. Archaeological Report 

Arch Reports: 

Archaeological Report (MC 612, 613, 656, 657, 701): 

Marmaduke & Assoc, LLS. Cultural Resource Evaluation, Mississippi Canyon Blocks 612, 613, 656, 

657, & 701, dated August 5, 2005. Data includes: Deep-tow side-scan sonar and sub-bottom 

profiler. 

Archaeological Conclusions and Recommendations (MC 612, 613, 656, 657, 701): 

Marmaduke & Associates, LLC recommends that Shell Offshore treat Sonar Target No. 5 as a possible 

significant shipwreck and immediately report it to the Minerals Management Service as a discovery. 

All operations, including even cursory inspection of the sea floor, should be suspended immediately 

within 600 meters (1,969 feet) of the site, and should not be resumed until the Regional Director of 

the Minerals Management Service instructions Shell Offshore on what steps to take to assess the 

potential historical significance of the site, and on what measures must be taken to protect it should 

it be determined to be historically significant. Under no circumstances should Shell Offshore, Inc. or 

any of its contractors and consultants, disturb the materials at Target No. 5 without the knowledge 

and approval of the Regional Director. 

Other targets reported here – with the exception of the COMPATT transponders – are too small to be 

wrecks, probably, in their own right. The possibility cannot be dismissed, however, that one or more 

of these targets may be dispersed wreckage associated with the sinking of the possible vessel 

identified here as Target No. 5. All of these other targets should be treated, therefore, as contacts of 

possible archaeological significance and should be avoided by 200 meters (656 feet) unless ROV 

inspection proved them to be modern man-made objects or natural phenomena. Unfortunately nine 

of the targets have insufficiently accurate location information to make a reasonable avoidance 

recommendation. These targets, however, are located somewhere outside of the basic survey grid 

during the lead in and lead out of survey lines, along with line turns. 

Archaeological Report (MC 657, 701, DC 617, 661): 

C&C Technologies. Archaeological Assessment “Shallow Coulomb” Prospect, Blocks 657 (OCS-G09496), 701 (OCS-G-21183), Mississippi Canyon Area, and 617 (CS-G-23525), and 661 (Unleased), 

Desoto Canyon Area, Project No. 061829, dated December 2006. Data includes: AUV side-scan 

sonar and sub-bottom profiler. 

Archaeological Conclusions and Recommendations (MC 657, 701, DC 617, 661): 

Data assessment for this portion of the “Coulomb” Prospect located thirty-seven unidentified sonar 

contacts including thirty-five isolated targets, one debris zone, and a shipwreck. Thirty-one of the 

isolated finds are considered modern debris or geologic features and are not recommended for 

archaeological avoidance or investigation. Four of the isolated sonar contacts may represent outlying 

shipwreck debris. These contacts (Nos. 2, 3, 7 and 8) are within the wreck’s existing avoidance zone. 

No additional avoidances are recommended. If an ROV investigation of the wreck is conducted, 

these targets should be investigated to verify they are shipwreck debris. 

A single debris zone was noted in the survey area. The field is likely modern or geologic. This debris 

zone is not considered to have historic potential based on its acoustic signature and is not 

recommended for archaeological avoidance or investigation. 

A previously located shipwreck site was investigated during this survey. The wreck was originally 

located during 1986 deep-tow survey. The acoustic data was analyzed and compared to recently 

investigated deepwater shipwrecks in the Green Canyon and Viosca Knoll Areas. The analysis 

suggests the MC 657 shipwreck is probably an historic wooden sailing vessel, possibly copper-clad, 

embedded up to six feet into the seafloor. The vessel’s lower hull may be intact beneath the bottom 

sediments. The hypothesis that the vessel is copper-clad is based on a comparison of the sonar 

Page 42 Public Information Copy
reflectivity with several known copper-clad vessels (including the Petronius Wreck in the Viosca Knoll 

Area). High-resolution side scan sonar data of the Petronius Wreck is available and a recent ROV 

investigation confirmed that it is a wooden hull copper-clad sailing vessel. Comparison of the side 

scan imagery shows distinct similarities in reflectivity between the Petronius Wreck and the MC 657 

wreck. 

It is recommended that the 2,000-ft avoidance zone previously established by the Minerals 

Management Service be maintained. It is also suggested that if the opportunity occurs, a ROV survey 

of the wreck site be conducted under the supervision of a qualified marine archaeologist to determine 

its historical importance. 

It is possible another shipwreck exists undetected or unidentified within the survey area. If wood 

beams, planking, ceramics, or other possible cultural materials are encountered during lease 

development, the MMS archaeologists should be contacted within 48 hours for an assessment of any 

antiquities. In this event, no activities should be conducted near the area or discovery until advised 

by the appropriate personnel. 

Archaeological Report (DC 573): 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 

617 (Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. 

Data includes: re-processed 3-D seismic, AUV side-scan sonar and sub-bottom profiler. 

Archaeological Conclusions and Recommendations (DC573) 

None of the unidentified side-scan sonar contacts in the 2013 AUV Survey Area are recommended for 

archaeological avoidance or investigation; however, care should be taken when working near all of 

the unidentified side-scan sonar contacts to prevent potential damage or impact to development 

infrastructure. A standard 100-ft geohazard avoidance is recommended for these contacts. 

J. Air and Water Quality Information 

Pursuant to NTL No. 2008-G04 the proposed operations covered by this plan 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, Section 18. 

K. Socioeconomic Information 

Pursuant to NTL No. 2008-G04 the proposed operations covered by this plan do not require Shell to 

provide additional information relating to socioeconomic information. For specific information relating 

to socioeconomic information please refer to the EIA, Section 18. 

Page 43 Public Information Copy
Attachment 6A – ESR for Well C-4 & C-5 

Page 44 Public Information Copy
SECTION 7: WASTE AND DISCHARGE INFORMATION 

A. Projected Generated Wastes 

Type of Waste and Composition Composition Projected Amount (Total) Discharge rate (per well) Discharge Method Answer yes or no

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

EXAMPLE: Cuttings wetted with ynthetic based fluid Cuttings generated while using synthetic 

based drilling fluid.

X bbl/well X bbl/day discharge pipe No

Water-based drilling fluid barite, additives, mud 184,956 bbls 2,151 bbls/day Seafloor discharge prior to marine riser 

installation No

Cuttings wetted with water-based fluid Cuttings coated with water based drilling 

mud 2,903 bbls 34 bbls/day Seafloor discharge prior to marine riser installation No

Cuttings wetted with synthetic-based fluid Cuttings generated while using synthetic 

based drilling fluid 1,979 bbls 23 bbls/day Cuttings chute below MSL No

Synthetic based drilling fluid adhering to washed drill 

cuttings

Synthetic based drilling fluid adhering to 

washed drill cuttings 136 bbls 2 bbls/day Cuttings chute below MSL No

Will humans be there? If yes, expect conventional waste

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

Domestic waste (kitchen water, shower water) grey water 32,035 bbls 215 bbls/day Ground to less than 25 mm mesh size 

and discharge overboard No

Sanitary waste (toilet water) treated sanitary waste 14,900 bbls 100 bbls/day Treated in the MSD** prior to discharge 

to meet NPDES limits No

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

Deck Drainage Wash and rainwater 1,490 bbls 10 bbls/day Drained overboard through deck 

scuppers

No

Will you conduct well treatment, completion, or workover? 

Well Treatment Fluids Water based frac fluids. Solvent based pipe 

pickle 3,000 bbls 94 bbls/day

Frac fluids will be injected in the well 

during the completion and will be flowed 

back to the host facility when the well is 

brought online. Returns will be minimal 

and will undergo static sheen testing 

and monthly grease compliance testing 

prior to discharge overboard. Pipe pickle 

to be collected and disposed of onshore.

No

Well Completion Fuids Calcium Bromide brine 12,000 bbls 375 bbls/day

Base plan is to catch all brine and return 

onshore for reclaim. In the event that 

this cannot happen, returns will undergo 

static sheen testing and monthly 

grease compliance testing prior to 

discharge overboard.

No

Well Clean Up Fluids

Base oil 

Transition Spacer 

Solvent based sweep 

Viscous Spacer 

NaCl brine (riser clean out) 

CaBr2 Brine (wellbore clean out)

12,000 bbls 375 bbls/day

Base oil will be caught with SBM and 

taken onshore. Transition Spacer will be 

caught and taken onshore for 

disposal.Solvent based sweep will be 

caught and taken onshore for disposal. 

Viscous spacer and NaCl will undergo 

static sheen testing and monthly grease 

compliance and be discharged 

overboard. CaBr2 will be reclaimed.

No

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

Desalinization unit discharge Rejected water from watermaker unit 1,419 bbls 400 gal/day Discharged overboard 35 feet below 

waterline No

Blowout prevent fluid Water based 0,089 bbls 0.6 bbls/day Disharge at seafloor No

Ballast water Uncontaminated seawater 685,400 bbls 4,600 bbls/day Discharged overboard just above 

waterline No

Bilge water Bilge and drainage water will be treated to 

MARPOL standards (< 15ppm oil in water). 27,565 bbls 185 bbls/day

Bilge and drainage water will be treated 

to MARPOL standards (< 15ppm oil in 

water).

No

Excess cement at seafloor Cement slurry 62,580 bbls 420 bbls/well Discharged at the seafloor during 

riserless drilling No

Fire water Treated seawater 19,459,400 bbls 130,600 bbls/day Drained overboard through deck 

scuppers

No

Cooling water Treated seawater 19,459,400 bbls 130,600 bbls/day Discharged overboard 40 feet below 

waterline No

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

Produced water NA NA NA NA NA

Will you be covered by an individual or general NPDES permit ? GMG 290103

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

Projected 

Downhole 

Projected generated waste Projected ocean discharges Disposal

Note: Please specify if the amount reported is a total or per well amount Supplmental DOCD: Coulomb

Page 45 Public Information Copy
B. Projected Ocean Discharges 

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 or dedicated tanks on support 

vessels MI Drilling Fluids - Fourchon, LA 7,000 bbls/well Recycled

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

Cuttings wetted with Synthetic-based fluid 

Drill cuttings from synthetic 

based interval. Storage tank on supply boat Newpark Environmental, Fourchon, LA 150 bbls / well Recycled

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

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

Produced sand

NA-well will have sand 

control NA NA NA NA

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

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

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA 22,400 lbs/well 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

11,200 lbs/well Landfill

used oil used oil Drums on supply boat

Omega Waste Management, W. 

Patterson, LA or ARC, New Iberia, LA

55 bbls/well Incinerate

Chemical product wastes Solvent

Captured at surface in MPT tanks, 

transported onshore for disposal in an 

environmentally friendly manner.

Safety Kleep, Denton, TX or Lamp 

Environmental, Hammond, LA

150 bbls/well Recycled

Waste Disposal

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

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

fill in the appropriate rows. 

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

Projected generated waste

Supplmental DOCD: Coulomb

C. Modeling Report 

 Not applicable to this Plan

Page 46 Public Information Copy
SECTION 8: AIR EMISSIONS INFORMATION 

A. Emissions Worksheet and Screening Questions 

Screening Questions for DOCD’s Yes No

Is any calculated Complex Total (CT) Emission amount (in tons) associated with 

your proposed exploration activities more than 90% of the amounts calculated 

using the following formulas: CT = 3400D2/3 for CO, and CT = 33.3D for the other 

air pollutants (where D = distance to shore in miles)?

X

Do your emission calculations include any emission reduction measures or modified 

emission factors?

X

Does or will the facility complex associated with your proposed development and 

production activities process production from eight or more wells?

X

Do you expect to encounter H2S at concentrations greater than 20 parts per million 

(ppm)?

X

Do you propose to flare or vent natural gas in excess of the criteria set forth under 

250.1105(a)(2) and (3)?

X

Do you propose to burn produced hydrocarbon liquids? X

Are your proposed development and production activities located within 25 miles 

from shore?

X

Are your proposed development and production activities located within 200 

kilometers of the Breton Wilderness Area?

X

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

provide: 

(1) Summary information regarding the peak year emissions for both Plan Emissions and 

Complex Total Emissions, if applicable. This information is compiled on the summary 

form of the two sets of worksheets. You can submit either these summary forms or use 

the format below. You do not need to include the entire set of worksheets. 

Air Pollutant Plan 

EmissionAmounts

(tons)

Calculated 

Exemption

Amounts 

(tons)

Calculated

Complex Total 

Emission 

Amounts

(tons)

Carbon monoxide CO

Particulate matter (PM)

Sulphur dioxide (SO2)

Nitrogen oxides (NOx)

Volatile organic compounds 

(VOC)

(2) Contact: Tracy Albert, 504.425.4652. Tracy.albert@shell.com

See attached worksheets for fuel limit basis and rig types proposed in this plan. 

Page 47 Public Information Copy
Fuel Limit Basis for Drillships and DP Semi-subs

jbm - 6/27/13

Purpose

Step 1 - Determine Typical Operating Loads

Scenario 1 – Riser less drilling (top hole) - Four engines online @ 35 to 45%

Scenario 2 - Riser less drilling Running casing/ cementing - Four Engines online @ 30 to 40 %

Scenario 3 - Transit (5 knot log speed) - Four engines online @ 65% . Not considered further 

Scenario 4 – Drilling ahead with BOP deployed - Four Engines online @ 40 to 50% 

 

Op Mode 1 Op Mode 2 Op Mode 3 Op Mode 4

45% 40% 50%

45% 40% 50%

45% 40% 50%

45% 40% 50%

0% 0% 0%

0% 0% 0%

30% 27% 33%

Step 2 - Identify Corresponding Fuel Levels

Value

74615

33%

25,000

3.88

Step 3 - Support Vessel Fuel Loads

Value

50%

10,943

5,471

6,260

939

1.10

Additional Notes

1 - Operating loads are campaign specific and may change in future AQRs depending on the future fuel usage tracking. Fuel levels 

depicted in this AQR does not restrict Shell from using a different value in future AQRs.

2 - If tracked fuel usage associated with this activity indicates emissions may exceed the approved emissions, Shell will submit 

revised AQR calculations.

3 - Shell is not utilizing fuel load restrictions for the Installation Vessels. This equipment is estimated at the relevant vessel capacity 

levels.

PTE Fuel Use (gal/day) Crew Vessels are rated at 5400 hp. The PTE fuel use is then estimated using the 

AQR conversion factor of 0.0483 gal/hp-hr.

Campaign Average Daily Fuel Use 

(gal/day)

Calculated Value - PTE fuel use * Proposed Operating Load. Note that Crew 

Vessels are only in field 30% of campaign and daily average value has been 

adjusted accordingly. Total Vessel Activity

CY2015-2016 Fuel Limits MMGals Sum of (vessel daily fuel use * corresponding campaign days)

Proposed Operating Load See Step 1 above.

Campaign Average Daily Fuel Use 

(gal/day)

Calculated Value - PTE fuel use * Proposed Operating Load and rounded up to 

nearest thousand (for additional conservatism).

Crew Vessel

CY2015-2016 Fuel Limits MMGals Calculated Value - Campaign Average Daily Fuel Use * Campaign Days 

Description Notes

Proposed Operating Loads Shell policy restricts D/P to < 50% near rig. When in standby away from rig but 

within 25 miles load will be < 50% (conserve fuel). When transiting through field 

(25 nm), traveling at economical speeds. 

Offshore Support Vessels

 PTE Fuel Use (gal/day) Offshore Support Vessels are rated at 9440 hp. The PTE fuel use is then 

estimated using the AQR conversion factor of 0.0483 gal/hp-hr.

Campaign Average Daily Fuel Use 

(gal/day)

Calculated Value - PTE fuel use * Proposed Operating Load. 

4 - Note the above fuel limits pertain to DP MODUs (Drillship and Semi-sub). If an anchored MODU is utilized, fuel limits 

are not necessary to remain below the relevant BOEM exemption thresholds.

Description Notes

Shell has reviewed engine information for its GOM fleet of Drillship and DP semi-sub MODUs. The single MODU with the largest 

power profile is the Noble Don Taylor, which has six main engines of 10,728 hp/engine. The projected fuel usages presented below 

would therefore be conservative across the fleet of Drillships and DP Semi-subs.

The Noble Don Taylor has six main engines. As confirmed by drillship owner, the below operating scenarios are considered 

representative for newbuild drilling rigs. Scenario 4 is selected as the conservative representation of typical engine loads. The 

highlighted cell indicates the highest power load scenario for this activity - Note Scenario 3 (transit) will be limited in duration and not 

considered representative for the full campaign. 

% Load

Engine

1

2

3

4

5

6

Average 

PTE Fuel Use (gal/day) The Noble Don Taylor is equipped with 6 main engines at 10,728 hp each. The 

PTE fuel use is then estimated using the AQR conversion factor of 0.0483 gal/hphr.

Page 48 Public Information Copy
COMPANY Shell Offshore Inc.

AREA Mississippi Canyon

BLOCK 657

LEASE OCS-G-09496

PLATFORM MODU (Multiple Types Presented)

WELL C-4 and C-5

COMPANY CONTACT Jeff McMenis

TELEPHONE NO. 504-425-6021

REMARKS SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

Page 49 Public Information Copy
Fuel Usage Conversion 

Factors

Natural Gas 

Turbines

Natural 

Gas 

Engines

Diesel 

Recip. 

Engine

REF. DATE

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

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

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

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

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

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

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

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

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

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

14-3

7/98

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

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

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

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

Glycol Dehydrator Vent lbs/mmscf 6.6 La. DEQ 1991

Gas Venting lbs/scf 0.0034

Sulphur Content Source Value Units

Fuel Gas 3.33 ppm

Diesel Fuel 0.05 % weight

Per 40 CFR 80.510(a)(1), Locomotive and Marine (LM) diesel fuels are limited to 500 ppm 

maximum sulfur, effective June 1, 2007.

Produced Gas( Flares) 3.33 ppm

Produced Oil (Liquid Flaring) 1 % weight

Page 50 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

DP MODU PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

DP Drillship or DP 

Semi-sub PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

Energency Generator>600hp 

diesel 2547 123 1 155 1.80 1.03 61.71 1.85 13.46

Emergency Air Compressor< 

600hp diesel 26 1 1 155 0.06 0.01 0.80 0.06 0.17

All other rig-equipment is electric (e.g cranes) or negligible in emissions potential (e.g. life boats, welding equipment, etc.)

Support Vessels Supply Vessel>600hp diesel 

(general support) 9440 456 5471 24 155 6.65 3.82 228.72 6.86 49.90 6.19 3.55 212.71 6.38 46.41

Supply Vessel>600hp diesel 

(spud activity) 9440 456 5471 24 10 6.65 3.82 228.72 6.86 49.90 0.40 0.23 13.72 0.41 2.99

Supply Vessel>600hp diesel 

(spud activity) 9440 456 5471 24 10 6.65 3.82 228.72 6.86 49.90 0.40 0.23 13.72 0.41 2.99

Crew Vessel>600hp diesel 5400 261 939 24 155 3.81 2.18 130.84 3.93 28.55 1.06 0.61 36.50 1.10 7.96

FACILITY Flowline Installation Vessel - Diesel 45000 2174 52164 24 10 31.72 18.19 1090.31 32.71 237.89 3.81 2.18 130.84 3.93 28.55

INSTALLATION Umbilical Installation Vessel - 51216 2474 59370 24 0 36.10 20.70 1240.92 37.23 270.75 0.00 0.00 0.00 0.00 0.00

Ocean Service Jumper Vessel - 23000 1111 26662 24 31 16.21 9.30 557.27 16.72 121.59 6.03 3.46 207.30 6.22 45.23

Construction Support Vessel - 23000 1111 26662 24 1 16.21 9.30 557.27 16.72 121.59 0.19 0.11 6.69 0.20 1.46

MISC. BPD SCF/HR COUNT

TANKDRILLING OIL BURN

WELL TEST GAS FLARE

2015 YEAR TOTAL 171.23 98.17 5884.86 176.59 1283.97 46.35 26.58 1593.41 47.80 347.65

EXEMPTION 

CALCULATION

DISTANCE FROM LAND IN 

MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE: Emissions for DP MODU activities in 2015 and 2016 account for reduced fuel usage. CY2017-2027 represent workover years and emissions are estimated at the Potential to Emit (no fuel reduction measures).

25000 28.27 16.21 971.92 29.16 212.06

Page 51 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

DP MODU PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

DP Drillship or DP 

Semi-sub PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

PRIME MOVER>600hp diesel 10728 518 24 155 7.56 4.34 259.93 7.80 56.71

Energency Generator>600hp 

diesel 2547 123 1 155 1.80 1.03 61.71 1.85 13.46

Emergency Air Compressor< 

600hp diesel 26 1 1 155 0.06 0.01 0.80 0.06 0.17

All other rig-equipment is electric (e.g cranes) or negligible in emissions potential (e.g. life boats, welding equipment, etc.)

Support Vessels Supply Vessel>600hp diesel 

(general support) 9440 456 5471 24 155 6.65 3.82 228.72 6.86 49.90 6.19 3.55 212.71 6.38 46.41

Supply Vessel>600hp diesel 

(spud activity) 9440 456 5471 24 10 6.65 3.82 228.72 6.86 49.90 0.40 0.23 13.72 0.41 2.99

Supply Vessel>600hp diesel 

(spud activity) 9440 456 5471 24 10 6.65 3.82 228.72 6.86 49.90 0.40 0.23 13.72 0.41 2.99

Crew Vessel>600hp diesel 5400 261 939 24 155 3.81 2.18 130.84 3.93 28.55 1.06 0.61 36.50 1.10 7.96

FACILITY Flowline Installation Vessel - Diesel 45000 2174 52164 24 0 31.72 18.19 1090.31 32.71 237.89 0.00 0.00 0.00 0.00 0.00

INSTALLATION Umbilical Installation Vessel - 51216 2474 59370 24 21 36.10 20.70 1240.92 37.23 270.75 9.10 5.22 312.71 9.38 68.23

Ocean Service Jumper Vessel - 23000 1111 26662 24 3 16.21 9.30 557.27 16.72 121.59 0.58 0.33 20.06 0.60 4.38

Construction Support Vessel - 23000 1111 26662 24 0 16.21 9.30 557.27 16.72 121.59 0.00 0.00 0.00 0.00 0.00

MISC. BPD SCF/HR COUNT

TANKDRILLING OIL BURN

WELL TEST GAS FLARE

2016 YEAR TOTAL 171.23 98.17 5884.86 176.59 1283.97 50.50 28.96 1736.09 52.08 378.78

EXEMPTION 

CALCULATION

DISTANCE FROM LAND IN 

MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE: Emissions for DP MODU activities in 2015 and 2016 account for reduced fuel usage. CY2017-2027 represent workover years and emissions are estimated at the Potential to Emit (no fuel reduction measures).

25000 32.78 18.79 1126.65 33.80 245.81

Page 52 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

DP MODU PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

DP Drillship or DP 

Semi-sub PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

PRIME MOVER>600hp diesel 10728 518 12436 24 60 7.56 4.34 259.93 7.80 56.71 5.44 3.12 187.15 5.61 40.83

Energency Generator>600hp 

diesel 2547 123 2952 1 60 1.80 1.03 61.71 1.85 13.46 0.05 0.03 1.85 0.06 0.40

Emergency Air Compressor< 

600hp diesel 26 1 30 1 60 0.06 0.01 0.80 0.06 0.17 0.00 0.00 0.02 0.00 0.01

All other rig-equipment is electric (e.g cranes) or negligible in emissions potential (e.g. life boats, welding equipment, etc.)

Support Vessels Supply Vessel>600hp diesel 

(general support) 9440 456 10943 24 60 6.65 3.82 228.72 6.86 49.90 4.79 2.75 164.68 4.94 35.93

Supply Vessel>600hp diesel 

(spud activity)

Supply Vessel>600hp diesel 

(spud activity)

Crew Vessel>600hp diesel 5,400 261 6260 24 60 3.81 2.18 130.84 3.93 28.55 2.74 1.57 94.20 2.83 20.55

FACILITY Flowline Installation Vessel - Diesel

INSTALLATION Umbilical Installation Vessel - 

Ocean Service Jumper Vessel - 

Construction Support Vessel - 

MISC. BPD SCF/HR COUNT

TANKDRILLING OIL BURN

WELL TEST GAS FLARE

2017-2027 YEAR TOTAL 57.68 33.05 1981.65 59.49 432.36 40.25 23.08 1383.65 41.51 301.89

EXEMPTION 

CALCULATION

DISTANCE FROM LAND IN 

MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE: Emissions for DP MODU activities in 2015 and 2016 account for reduced fuel usage. CY2017-2027 represent workover years and emissions are estimated at the Potential to Emit (no fuel reduction measures were applied).

Page 53 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

Anchored MODU Wartsila Diesel Generator Engine 1 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 2 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 3 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 4 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Diesel Crane Engine 1 575 28 667 12 155 1.27 0.23 17.73 1.42 3.84 1.18 0.22 16.49 1.32 3.57

Diesel Crane Engine 2 575 28 667 12 155 1.27 0.23 17.73 1.42 3.84 1.18 0.22 16.49 1.32 3.57

Emergency Diesel Generator Engine 850 41 985 3 6 0.60 0.34 20.59 0.62 4.49 0.01 0.00 0.19 0.01 0.04

Cement Unit Engine (CMU-1) 1,800 87 2087 24 8 1.27 0.73 43.61 1.31 9.52 0.12 0.07 4.19 0.13 0.91

Cement Unit Engine (CMU-2) 490 24 568 24 8 1.08 0.20 15.11 1.21 3.27 0.10 0.02 1.45 0.12 0.31

All other rig-equipment is electric or negligible in emissions potential (e.g. life boats, rescue-boats, etc.)

SUPPORT Supply Vessel>600hp diesel (general 

support) 9,440 456 10943 24 155 6.65 3.82 228.72 6.86 49.90 12.38 7.10 425.42 12.76 92.82

VESSEL Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 10 6.65 3.82 228.72 6.86 49.90 0.80 0.46 27.45 0.82 5.99

Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 10 6.65 3.82 228.72 6.86 49.90 0.80 0.46 27.45 0.82 5.99

Crew Vessel>600hp diesel 5,400 261 6260 24 47 3.81 2.18 130.84 3.93 28.55 2.15 1.23 73.79 2.21 16.10

Anchor Handling Vessel>600 hp 

diesel 30,000 1449 34776 24 10 21.15 12.13 726.87 21.81 158.59 2.54 1.46 87.22 2.62 19.03

Anchor Handling Vessel>600 hp 

diesel 21,600 1043 25039 24 10 15.22 8.73 523.35 15.70 114.19 1.83 1.05 62.80 1.88 13.70

Anchor Handling Vessel>600 hp 

diesel 13,500 652 15649 24 10 9.52 5.46 327.09 9.81 71.37 1.14 0.65 39.25 1.18 8.56

Tug Boat Vessel>600 hp 16,500 797 19127 24 5 11.63 6.67 399.78 11.99 87.22 0.70 0.40 23.99 0.72 5.23

Tug Boat Vessel>600 hp 13,500 652 15649 24 5 9.52 5.46 327.09 9.81 71.37 0.57 0.33 19.63 0.59 4.28

Pipeline Flowline Installation Vessel - Diesel 45,000 2174 52164 24 10 31.72 18.19 1090.31 32.71 237.89 3.81 2.18 130.84 3.93 28.55

INSTALLATION Umbilical Installation Vessel - Diesel 51,216 2474 59370 24 0 36.10 20.70 1240.92 37.23 270.75 0.00 0.00 0.00 0.00 0.00

Ocean Service Jumper Vessel - 

Diesel 23,000 1111 26662 24 31 16.21 9.30 557.27 16.72 121.59 6.03 3.46 207.30 6.22 45.23

Construction Support Vessel - Diesel 23,000 1111 26662 24 1 16.21 9.30 557.27 16.72 121.59 0.19 0.11 6.69 0.20 1.46

PRODUCTION

DRILLING OIL BURN

WELL TEST GAS FLARE

2015 YEAR TOTAL 215.15 121.97 7322.35 222.20 1597.51 70.18 39.28 2362.18 72.59 515.32

EXEMPTION 

CALCULATION DISTANCE FROM LAND IN MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE - Emissions for Anchored MODU activities are estimated at the Potential to Emit (no fuel reduction measures).

Page 54 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

Anchored MODU Wartsila Diesel Generator Engine 1 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 2 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 3 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Wartsila Diesel Generator Engine 4 6,610 319 7662 24 155 4.66 2.67 160.15 4.80 34.94 8.67 4.97 297.89 8.94 64.99

Diesel Crane Engine 1 575 28 667 12 155 1.27 0.23 17.73 1.42 3.84 1.18 0.22 16.49 1.32 3.57

Diesel Crane Engine 2 575 28 667 12 155 1.27 0.23 17.73 1.42 3.84 1.18 0.22 16.49 1.32 3.57

Emergency Diesel Generator Engine 850 41 985 3 6 0.60 0.34 20.59 0.62 4.49 0.01 0.00 0.19 0.01 0.04

Cement Unit Engine (CMU-1) 1,800 87 2087 24 8 1.27 0.73 43.61 1.31 9.52 0.12 0.07 4.19 0.13 0.91

Cement Unit Engine (CMU-2) 490 24 568 24 8 1.08 0.20 15.11 1.21 3.27 0.10 0.02 1.45 0.12 0.31

All other rig-equipment is electric or negligible in emissions potential (e.g. life boats, rescue-boats, etc.)

SUPPORT Supply Vessel>600hp diesel (general 

support) 9,440 456 10943 24 155 6.65 3.82 228.72 6.86 49.90 12.38 7.10 425.42 12.76 92.82

VESSEL Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 10 6.65 3.82 228.72 6.86 49.90 0.80 0.46 27.45 0.82 5.99

Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 10 6.65 3.82 228.72 6.86 49.90 0.80 0.46 27.45 0.82 5.99

Crew Vessel>600hp diesel 5,400 261 6260 24 47 3.81 2.18 130.84 3.93 28.55 2.15 1.23 73.79 2.21 16.10

Anchor Handling Vessel>600 hp 

diesel 30,000 1449 34776 24 10 21.15 12.13 726.87 21.81 158.59 2.54 1.46 87.22 2.62 19.03

Anchor Handling Vessel>600 hp 

diesel 21,600 1043 25039 24 10 15.22 8.73 523.35 15.70 114.19 1.83 1.05 62.80 1.88 13.70

Anchor Handling Vessel>600 hp 

diesel 13,500 652 15649 24 10 9.52 5.46 327.09 9.81 71.37 1.14 0.65 39.25 1.18 8.56

Tug Boat Vessel>600 hp 16,500 797 19127 24 5 11.63 6.67 399.78 11.99 87.22 0.70 0.40 23.99 0.72 5.23

Tug Boat Vessel>600 hp 13,500 652 15649 24 5 9.52 5.46 327.09 9.81 71.37 0.57 0.33 19.63 0.59 4.28

Pipeline Flowline Installation Vessel - Diesel 45,000 2174 52164 24 0 31.72 18.19 1090.31 32.71 237.89 0.00 0.00 0.00 0.00 0.00

INSTALLATION Umbilical Installation Vessel - Diesel 51,216 2474 59370 24 21 36.10 20.70 1240.92 37.23 270.75 9.10 5.22 312.71 9.38 68.23

Ocean Service Jumper Vessel - 

Diesel 23,000 1111 26662 24 3 16.21 9.30 557.27 16.72 121.59 0.58 0.33 20.06 0.60 4.38

Construction Support Vessel - Diesel 23,000 1111 26662 24 0 16.21 9.30 557.27 16.72 121.59 0.00 0.00 0.00 0.00 0.00

PRODUCTION

DRILLING OIL BURN

WELL TEST GAS FLARE

2016 YEAR TOTAL 215.15 121.97 7322.35 222.20 1597.51 69.82 39.08 2350.12 72.23 512.69

EXEMPTION 

CALCULATION DISTANCE FROM LAND IN MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE - Emissions for Anchored MODU activities are estimated at the Potential to Emit (no fuel reduction measures).

Page 55 Public Information Copy
COMPANY AREA BLOCK LEASE PLATFORM WELL CONTACT PHONE REMARKS

 Shell Offshore Inc. Mississippi Canyon 657 OCS-G-09496 MODU (Multiple Types Presented) C-4 and C-5 Jeff McMenis 504-425-6021 SEPCO Environmental File - Coulomb-AQR-DOCD-AnyMODU=021414.xlsx

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

Diesel Engines HP GAL/HR GAL/D

Nat. Gas Engines HP SCF/HR SCF/D

Burners MMBTU/HR SCF/HR SCF/D HR/D DAYS P M SOx NOx VOC CO P M SOx NOx VOC CO

Anchored MODU Wartsila Diesel Generator Engine 1 6,610 319 7662 24 60 4.66 2.67 160.15 4.80 34.94 3.35 1.92 115.31 3.46 25.16

Wartsila Diesel Generator Engine 2 6,610 319 7662 24 60 4.66 2.67 160.15 4.80 34.94 3.35 1.92 115.31 3.46 25.16

Wartsila Diesel Generator Engine 3 6,610 319 7662 24 60 4.66 2.67 160.15 4.80 34.94 3.35 1.92 115.31 3.46 25.16

Wartsila Diesel Generator Engine 4 6,610 319 7662 24 60 4.66 2.67 160.15 4.80 34.94 3.35 1.92 115.31 3.46 25.16

Diesel Crane Engine 1 575 28 667 12 60 1.27 0.23 17.73 1.42 3.84 0.46 0.08 6.38 0.51 1.38

Diesel Crane Engine 2 575 28 667 12 60 1.27 0.23 17.73 1.42 3.84 0.46 0.08 6.38 0.51 1.38

Emergency Diesel Generator Engine 850 41 985 3 2 0.60 0.34 20.59 0.62 4.49 0.00 0.00 0.06 0.00 0.01

Cement Unit Engine (CMU-1) 1,800 87 2087 24 8 1.27 0.73 43.61 1.31 9.52 0.12 0.07 4.19 0.13 0.91

Cement Unit Engine (CMU-2) 490 24 568 24 8 1.08 0.20 15.11 1.21 3.27 0.10 0.02 1.45 0.12 0.31

All other rig-equipment is electric or negligible in emissions potential (e.g. life boats, rescue-boats, etc.)

SUPPORT Supply Vessel>600hp diesel (general 

support) 9,440 456 10943 24 60 6.65 3.82 228.72 6.86 49.90 4.79 2.75 164.68 4.94 35.93

VESSEL Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 0 6.65 3.82 228.72 6.86 49.90 0.00 0.00 0.00 0.00 0.00

Supply Vessel>600hp diesel (spud 

activity) 9,440 456 10943 24 0 6.65 3.82 228.72 6.86 49.90 0.00 0.00 0.00 0.00 0.00

Crew Vessel>600hp diesel 5,400 261 6260 24 18 3.81 2.18 130.84 3.93 28.55 0.82 0.47 28.26 0.85 6.17

Anchor Handling Vessel>600 hp 

diesel 30,000 1449 34776 24 10 21.15 12.13 726.87 21.81 158.59 2.54 1.46 87.22 2.62 19.03

Anchor Handling Vessel>600 hp 

diesel 21,600 1043 25039 24 10 15.22 8.73 523.35 15.70 114.19 1.83 1.05 62.80 1.88 13.70

Anchor Handling Vessel>600 hp 

diesel 13,500 652 15649 24 10 9.52 5.46 327.09 9.81 71.37 1.14 0.65 39.25 1.18 8.56

Tug Boat Vessel>600 hp 16,500 797 19127 24 5 11.63 6.67 399.78 11.99 87.22 0.70 0.40 23.99 0.72 5.23

Tug Boat Vessel>600 hp 13,500 652 15649 24 5 9.52 5.46 327.09 9.81 71.37 0.57 0.33 19.63 0.59 4.28

Pipeline Flowline Installation Vessel - Diesel

INSTALLATION Umbilical Installation Vessel - Diesel

Ocean Service Jumper Vessel - 

Diesel

Construction Support Vessel - Diesel

PRODUCTION

DRILLING OIL BURN

WELL TEST GAS FLARE

2017-2027 YEAR TOTAL 114.91 64.49 3876.59 118.83 845.71 26.94 15.06 905.54 27.88 197.55

EXEMPTION 

CALCULATION DISTANCE FROM LAND IN MILES 2797.20 2797.20 2797.20 2797.20 65212.64

84.0

NOTE - Emissions for Anchored MODU activities are estimated at the Potential to Emit (no fuel reduction measures).

Page 56 Public Information Copy
Shell 

Offshore Inc.

Mississippi 

Canyon 657 OCS-G-09496

MODU 

(Multiple 

Types 

Presented)

C-4 and C-5

Emitted Substance

Year

PM SOx NOx VOC CO

AQR Emissions if DP MODU(Semi-sub or 

Drillship) is Utilized

2015 46.35 26.58 1593.41 47.80 347.65

2016 50.50 28.96 1736.09 52.08 378.78

2017-

2027 40.25 23.08 1383.65 41.51 301.89

AQR Emissions if Anchored MODU is 

Utilized

2015 70.18 39.28 2362.18 72.59 515.32

2016 69.82 39.08 2350.12 72.23 512.69

2017-

2027 26.94 15.06 905.54 27.88 197.55

Allowable 2797.20 2797.20 2797.20 2797.20 65212.64

Notes

1 - Emissions for DP MODU activities in 2015 and 2016 account for reduced fuel usage. CY2017-2027 

represent workover years and emissions are estimated at the Potential to Emit (no fuel reduction measures).

2 - Emissions for Anchored MODU activities are estimated at the Potential to Emit (no fuel reduction 

measures).

Page 57 Public Information Copy
Page 58 Public Information Copy
SECTION 9: OIL SPILL INFORMATION 

A. Oil Spill Response Planning 

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

Shell Offshore Inc. (0689) in accordance with 30 CFR 550 and 30 CFR 254, and approved by BSEE in 

April 2013. As show in the comparison table below, the operations proposed in this plan do not 

exceed the certificate amount on file with BSEE. 

Spill Response Sites: 

Primary Response Equipment Location Preplanned Staging Location(s)

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

Fort Jackson, LA

Fourchon, LA; Pascagoula, MS; Fort 

Jackson, LA; Venice, LA

OSRO Information: 

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

Associates (CGA), Marine Spill Response Company (MSRC), Clean Caribbean America (CCA), and 

OSRL/EARL. 

Worst Case Scenario Determination: 

Drilling Production

Category Regional OSRP DOCD Regional OSRP DOCD

Type of Activity Subsea 

Drilling

Coulomb

Drilling

Production >10 

miles to shore

Coulomb

Drilling

Facility Location (area/block) MC 391 MC 657 MC 807 MC 657

Facility Designation Subsea well 1◊ Subsea well #C-4 MB001◊◊ Subsea well #C-4

Distance to Nearest Shoreline (miles) 70 84 53 84

Volume

Storage tanks (total)

Flowlines (on facility)

Pipelines

Uncontrolled blowout (volume per day)

Total Volume

N/A

N/A

N/A

416,414* BOPD

416,414 BOPD

N/A

N/A

N/A

49,711** BOPD

49,711** BOPD

11,163 Bbls

100 Bbls

1,604 Bbls

446,000*** BOPD

458,867 Bbls

N/A

N/A

N/A

49,711** BOPD

49,711** BOPD

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

diesel)

Crude oil Crude oil Crude Oil Crude oil

API Gravity(s) 26o 27 o 26o 27 o

 *24 hour rate (391,808 BOPD 30 day average) 

 **24 hour rate (15,000 BOPD 30 day average rate) 

***24 hour rate (359,500 BOPD 30 day average rate) 

◊This well was reviewed and accepted by BOEM in plan S-7444 (May 2011) and accepted by BSEE during the drilling 

of the well. The 30-day average was updated in update to the OSRP July 2012. 

◊◊This well was review and accepted by BOEM in plan S-7499.

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

in its regional OSRP, approved by BSEE April 2013, and since the worst-case scenario determined for our 

Plan does not replace the appropriate worst-case scenario in our regional OSRP, I hereby certify that Shell 

Offshore Inc. has the capability to respond, to the maximum extent practicable, to a worst-case discharge, 

or a substantial threat of such a discharge, resulting from the activities proposed in our DOCD. 

Page 59 Public Information Copy
B. Oil Spill Response Discussion

1. Volume of the Worst Case Discharge 

Please refer to Section 2j and 9(iv) of this EP. 

2. Trajectory Analysis 

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

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

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

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

segment contact probabilities are shown in Table 9.C.1. 

Area/Block OCS-G

Launch

Area Land Segment Contact %

MC 654 9496 59

Cameron, LA 1

Vermilion, LA 1

Terrebonne, LA 2

Lafourche, LA 2

Jefferson, LA 1

Plaquemines, LA 11

St. Bernard, LA 2

Walton, FL 1

Bay, FL 1

Table 9.C.1 Probability of Land Segment Impact 

C. Resource Identification

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

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

identified using the appropriate National Oceanic and Atmospheric Administration (NOAA) 

Environmental Sensitivity Index (ESI) maps for the given land segment. ESI maps provide a 

concise summary of coastal resources that are at risk if an oil spill occurs nearby. Examples of atrisk resources include biological resources (such as birds and shellfish beds), sensitive shorelines 

(such as marshes and tidal flats), and human-use resources (such as public beaches and parks). 

In the event an oil spill occurs, ESI maps can help responders meet one of the main response 

objectives: reducing the environmental consequences of the spill and the cleanup efforts. 

Additionally, ESI maps can be used by planners to identify vulnerable locations, establish 

protection priorities, and identify cleanup strategies. 

The following is a list of resources of special economic or environmental importance that 

potentially could be impacted by the Mississippi Canyon 657 WCD scenario. 

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Onshore/Nearshore: Plaquemines Parish has been identified as the most probable impacted Parish 

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

Worst Case Discharge. Plaquemines Parish has a total area of 2,429 square miles of which, 845 

square miles of it is land and 1,584 square miles is water. Plaquemines Parish includes two National 

Wildlife Refuges: Breton National Wildlife Refuge and Delta National Wildlife Refuge. This area is also 

a nesting ground for the brown pelican, an endangered species. Examples of Environmental 

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

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

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

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

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

applicable. 

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

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

coordinated response to oil discharges and other hazardous releases. The One Gulf Plan is specific to 

the Gulf of Mexico to advance the unity of policy and effort in each of the Gulf Coast ACPs. Strategies 

used for the response to an oil spill regarding protection of identified resources are detailed in the 

One Gulf Plan and relevant Gulf Coast ACP. 

D. Worst Case Discharge Response 

Shell will make every effort to respond to the MC 657 Worst Case Discharge as effectively as 

possible. Below is a table outlining the applicable evaporation and surface dispersion quantity: 

Mississippi Canyon Block 657

Calculations

(BBLS)

i. TOTAL WCD (based on 30 day average (per day)) 88,459

ii. Loss of volume of oil to natural surface dispersion and evaporation (approximate 

bbls per day)

(12% Natural surface dispersion and evaporation in 24 hrs)*

-10,615

TOTAL REMAINING ~77,844

* As this blowout scenario involves a topside blowout onboard the platform, an ADIOS 2 Model 

was ran to account for surface dispersion and evaporation. 

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

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

adverse weather conditions, major response vessels and Transrec skimmers are still effective and 

safe in sea states of 6-8 ft. If sea conditions prohibit safe mechanical recovery efforts, then 

natural dispersion and airborne chemical dispersant application (visibility & wind conditions 

permitting) may be the only safe and viable recovery option. 

MSRC OSRV 8 foot seas

VOSS System 4 foot seas

Expandi Boom 6 foot seas, 20 knot winds

Dispersants Winds more than 25 knots,

Visibility less than 3 nautical miles, or

Ceiling less than 1,000 feet.

Table 9.D.2 Operational Limitations of Response Equipment 

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

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

subsea dispersant, shoreline protection, wildlife protection, and containment equipment. 

Following is a list of the contracted resources including de-rated recovery capacity, personnel, 

and estimated response times (procurement, load out, travel time to the site, and deployment). 

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The Incident Commander or designee may contact other service companies if the Unified 

Command deems such services necessary to the response efforts. 

Based on the anticipated worst case discharge scenario, Shell can be onsite with dedicated, 

contracted on water oil spill recovery equipment with adequate response capacity to contain and 

recover surface oil, and prevent land impact, within approximately 21 hours (based on the 

equipment’s Estimated Daily Response Capacity (EDRC)). Shell will continue to ramp up 

additional on-water mechanical recovery resources as well as apply dispersants and in-situ 

burning as needed and as approved under the supervision of the USCG Captain of the Port 

(COTP) and the Regional Response Team (RRT). 

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

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

contain oil flow in the unlikely event of an underwater well blowout, and is designed, 

constructed, tested, and available for rapid response. Shell’s specific containment response for 

MC 657 will be addressed in Shell’s NTL10 submission at the time the APD is submitted.

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

Mechanical Recovery (skimming): Response strategies include skimming utilizing available 

OSROs Oil Spill Response Vessels (OSRVs), Oil Spill Response Barges (OSRBs), ID Boats, and 

Quick Strike OSRVs. There is a combined de-rated recovery rate capability of approximately 

246,800 barrels/day. Temporary storage associated with the identified skimming and temporary 

storage equipment equals approximately 286,800 barrels. 

De-rated Recovery Rate

(bopd)

Storage

(bbls)

Offshore Recovery and 

Storage 191,679 194,749

Nearshore Recovery and 

Storage 233,856 12,516

Total 425,535 207,265

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

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

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

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

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

any other tanker immediately available). The recovered oil would be transferred to Motiva’s 

Norco, LA storage and refining facility, or would be stored at Delta Commodities, Inc. Harvey, LA 

facility.

Aerial Surveillance: Aircraft can be mobilized to detect, monitor, and target response to oil 

spills. Aircraft and spotters can be mobilized within hours of an event. 

Table 9.D.6 Aerial Surveillance Activation List

Aerial Dispersant: Depending on proximity to shore and water depth, dispersants may be a 

viable response option. If appropriate and approved, 4 to 5 sorties from three DC-3’s can be 

made within the first 12 hour operating day of the response. These aerial systems could disperse 

approximately 7,704 to 9,630 barrels of oil per day. Additionally, 3 to 4 sorties from the BE90 

King Air and 3 to 4 sorties from the Hercules C-130A within the first 12 hour operating day of the 

response could disperse 4,600 to 6,100 barrels of oil per day. For continuing dispersant 

operations, the CCA’s Aerial Dispersant Delivery System (ADDS) would be mobilized. The ADDS 

has a dispersant spray capability of 5,000 gallons per sortie. 

 Table 9.D.7 Offshore Aerial Dispersant Activation List 

Vessel Dispersant: Vessel dispersant application is another available response option. If 

appropriate, vessel spray systems can be installed on offshore vessels of opportunity using 

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inductor nozzles (installed on fire-water monitors), skid mounted systems, or purpose-built boom 

arm spray systems. Vessels can apply dispersant within the first 12-24 hours of the response and 

continually as directed. 

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

Subsea Dispersant: Shell has contracted with Wild Well Control for a subsea dispersant 

package. Subsea dispersant application has been found to be highly effective at reducing the 

amount of oil reaching the surface. Additional data collection, laboratory tests and field tests will 

help in facilitating the optimal application rate and effectiveness numbers. For planning purposes, 

the system has the potential to disperse approximately 24,500 to 34,000 barrels of oil per day.

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

In-Situ Burning: Open-water in-situ burning (ISB) also may be used as a response strategy, 

depending on the circumstances of the release. ISB services may be provided by the primary 

OSRO contractors. If appropriate conditions exist and approvals are granted, one or multiple ISB 

task forces could be deployed offshore. Task forces typically consist of two to four fire teams, 

each with two vessels capable of towing fire boom, guide boom or tow line with either a 

handheld or aerially-deployed oil ignition system. At least one support/safety boat would be 

present during active burning operations to provide logistics, safety and monitoring support. 

Depending upon a number of factors, up to 4 burns per 12-hour day could be completed per ISB 

fire team. Most fire boom systems can be used for approximately 8-12 burns before being 

replaced. Fire intensity and weather will be the main determining factors for actual burns per 

system. Although the actual amount of oil that will be removed per burn is dependent on many 

factors, recent data suggests that a typical burn might eliminate approximately 750 barrels. For 

planning purposes and based on the above assumptions, a single task force of four fire teams 

with the appropriate weather and safety conditions could complete four burns per day and 

remove up to ~12,000 bbls/day. In-situ burning nearshore and along shorelines may be a 

possible option based on several conditions and with appropriate approvals, as outlined in 

Section 19, In-situ Burn Plan (OSRP). In-situ burning along certain types of shorelines may be 

used to minimize physical damage where access is limited or if it is determined that 

mechanical/manual removal may cause a substantial negative impact on the environment. All 

safety considerations will be evaluated. In addition, Shell will assess the situation and can make 

notification within 48 hours of the initial spill to begin ramping up fire boom production through 

contracted OSRO(s). There are potential limitations that need to be assessed prior to ISB 

operations. Some limitations include atmospheric and sea conditions; oil weathering; air quality 

impacts; safety of response workers; and risk of secondary fires. 

 Table 9.D.10 In-Situ Burn Equipment Activation List 

 Shoreline Protection: If the spill went unabated, shoreline impact in Cameron Parish, LA would 

depend upon existing environmental conditions. Nearshore response may include the deployment 

of shoreline boom on beach areas, or protection and sorbent boom on vegetated areas. 

Strategies would be based upon surveillance and real time trajectories provided by The Response 

Group that depict areas of potential impact given actual sea and weather conditions. Strategies 

from the New Orleans, Louisiana Area Contingency Plan, Unified Command would be consulted to 

ensure that environmental and special economic resources would be correctly identified and 

prioritized to ensure optimal protection. Shell has access to shoreline response guides that depict 

the protection response modes applicable for oil spill clean-up operations. Each response mode is 

schematically represented to show optimum deployment and operation of the equipment in areas 

of environmental concern. Supervisory personnel have the option to modify the deployment and 

operation of equipment allowing a more effective response to site-specific circumstances. 

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

Wildlife Protection: If wildlife is threatened due to a spill, the contracted OSRO’s have 

resources available to Shell, which can be utilized to protect and/or rehabilitate wildlife. The 

resources under contract for the protection and rehabilitation of affected wildlife are in Table

9.D.11. 

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New or unusual technology in regards to spill, prevention, control and clean-up: 

Shell will use our normal well design and construction processes with multiple barrier approach as 

well as new stipulations mandated by NTL 05. Response techniques will utilize new learnings 

from Macondo response to include in-situ burning and subsea dispersant application. Mechanical 

recovery advancements are continuing to be made to incorporate utilization of Koseq arms 

outfitted on barges, conversion of Platform Support Vessels for Oil Spill Response, and inclusion 

of nighttime spill detection radar to improve tracking capabilities (X-Band radar, Infrared sensing, 

etc.). In addition, new response technologies/techniques are continuing to be considered by Shell 

and the appropriate government organizations for incorporation into our planned response. Any 

additional response technologies/techniques presented at the time of response will be used at 

the discretion of the Unified Command and USCG. 

 

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Figure 9.C.1 Environmental Sensitivity Index Map Legend 

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Figure 9.C.2 South Pass ESI Map 

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Figure 9.C.3 Garden Island Pass ESI Map 

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. 

Figure 9.C.4 Pass a Loutre West ESI Map 

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Figure 9.C.5 Main Pass ESI Map 

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

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

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Table 9.D.5 Nearshore On-Water Recovery Activation List 

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Table 9.D.5 Nearshore On-Water Recovery Activation List (continued) 

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Table 9.D.5 Nearshore On-Water Recovery Activation List (continued) 

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Table 9.D.5 Nearshore On-Water Recovery Activation List (continued) 

Table 9.D.6 Aerial Surveillance Activation List 

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Table 9.D.7 Offshore Aerial Dispersant Activation List 

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Table 9.D.7 Offshore Aerial Dispersant Activation List (Continued) 

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

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Table 9.D.9 Subsea Dispersant Package Activation List 

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Table 9.D.10 In-Situ Burn Equipment Activation List 

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Table 9.D.10 In-Situ Burn Equipment Activation List (continued) 

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Table 9.D.10 In-Situ Burn Equipment Activation List (continued) 

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Table 9.D.10 In-Situ Burn Equipment Activation List (continued) 

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Table 9.D.10 In-Situ Burn Equipment Activation List (continued) 

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

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Table 9.D.11 Shoreline Protection and Wildlife Support List (continued) 

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Table 9.D.11 Shoreline Protection and Wildlife Support List (continued) 

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Table 9.D.11 Shoreline Protection and Wildlife Support List (continued) 

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SECTION 10: ENVIRONMENTAL MONITORING INFORMATION 

A. Monitoring Systems 

A rig based Acoustic Doppler Current Profiler (ADCP) is used to continuously monitor the current beneath 

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

monitored. 

B. Incidental takes 

No incidental takes are anticipated. Although marine mammals may be seen in the area, Shell does not 

believe that its operations proposed under this plan will result Shell implements the mitigation measures 

and monitors for incidental takes of protected species according to the following notices to lessees and 

operators from the BOEM/BSEE: 

 NTL 2012-BSEE-G01 “Marine Trash and Debris Awareness and Elimination”

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

 NTL 2012-Joint-G02 “Implementation of Seismic Survey Mitigation Measures & Protected 

Species Observer Program”

C. Flower Garden Banks National Marine Sanctuary 

This block is not located in the Flower Garden Banks National Marine Sanctuary.

SECTION 11: LEASE STIPULATIONS INFORMATION 

Stipulation No. 1 – Protection of Archaeological Resources 

See Section 6 of this plan for information regarding Archaeological Resources. Shell is providing a new 

Archeological report for anchor coverage areas within DeSoto Canyon that required clearance. This report is 

being provided to BOEM with the submittal of this plan. 

Stipulation No. 4 – Military Areas 

Shell will enter into an agreement with the commander of the Eglin AFB in regards to the Eglin Water 

Test Area 1 and 3 prior to initiating operations and will coordinate with the command headquarters 

concerning the location, density and planned periods of operations proposed in this plan. Shell is aware 

of the condition for temporary suspension of operations and/or evacuation of the lease if dictated by 

national security issues and operators must coordinate proposed activities with BOEM to minimize 

conflicts with the Department of the Defense. 

SECTION 12: ENVIRONMENTAL MITIGATION MEASURE INFORMATION 

A. Impacts to Marine and coastal environments 

The proposed action will implement mitigation measures required by laws and regulations, including all 

applicable Federal & State requirements concerning air emissions, discharges to water, and solid waste 

disposal, as well as any additional permit requirements and Shell policies. Project activities will be 

conducted in accordance with the Regional Oil Spill Response Plan. The EIA in Section 18 of this plan 

discusses impacts and mitigation measures. 

B. Incidental Takes 

We do not anticipate any incidental takes related to the proposed operations. Shell implements the 

mitigation measures and monitors for incidental takes of protected species according to the following 

notices to lessees and operators from BOEM/BSEE: 

 NTL 2012-BSEE-G01 “Marine Trash and Debris Awareness and Elimination”

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

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 NTL 2012-Joint-G02 “Implementation of Seismic Survey Mitigation Measures & Protected 

Species Observer Program”

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SECTION 13: RELATED FACILITIES 

 AND OPERATIONS INFORMATION 

Coulomb Phase 2 Facilities 

The Coulomb Phase 2 subsea development includes a single 8.625” OD production flowline and a 4.5” OD 

Gas Lift Riser connected to the Na Kika host facility. The production flowline is approximately 143,800 

feet long with a riser based in-line sled (for gas lift tie-in), an inline sled (for well C-4 tie-in) and 

terminates at a Pipeline End Termination (PLET). The production flowline is connected to the Gas Lift 

Riser via a 80’, 6.625” OD jumper at the riser base gas-lift sled, connected via a 75’, 6.625” OD well 

jumper to the new C-4 well and a 72’ 8.625” OD flowline jumper connects the PLET to a new 131’, 8.625” 

truss jumper in turn that connects to the existing CG-1 sled via a 82’, 8.625” OD flowline jumper. 

Additionally a new 60’ long 6.625” OD well jumper will connect the existing C-2 well to the new truss 

jumper. 

The 4.5” Gas Lift Riser & Flowline is approximately 23,200’ and terminates at a riser based gas-lift sled 

that is connected to the Production Flowline by the previously mentioned 80’, 6.625” OD jumper to the 

riser based in-line sled. 

The Coulomb Phase 2 project also includes 3 new umbilicals in a single dynamic section plus two static 

sections to perform control functions and deliver chemicals to support the production operations of the 

subsea development. 

The flowlines/pipelines mentioned above will be right-of-way (ROW) pipelines and will be permitted under 

ROW permit applications with BSEE. 

Host Facilities 

The Na Kika Semi-Submersible was installed in 2003. Na Kika is the host facility for several subsea 

developments including Ariel, Coulomb, East Anstey, Herschel, Kepler, Na Kika 3 and Galapagos/Isebella. 

The Coulomb phase 2 project will use existing riser baskets and I-tube on Na Kika. 

Na Kika receives production fluids from the subsea wells and is separated into oil, gas and water. The 

gas and oil are exported via a 20”/24” gas export pipeline and an 18” oil export pipeline, the water is 

overboarded. 

Na Kika is designed to handle 135,000 BOPD, 450 MMSCFD with a water treating capacity of 50,000 

BWPD. Current production rates are 60,000 BOPD, 160 MMSCFD and 16,000 BWPD. 

A new inlet separator and flowline heater will be installed for Coulomb Phase 2 as well as chemical 

injection support facilities. This new equipment adds to the existing process system that consists of High 

Pressure Separators for each field, Oil and Gas Condensate Production Heaters, and a Bulk Oil Treater 

vessel delivering oil to the Dry Oil Tank and water to the water treating equipment. The facility has two 

low pressure compressors, one booster gas compressor, and one vapor recovery unit to recover solution 

gas from the Dry Oil Tank and process vessels. There are five turbine driven electric generators to supply 

power for the Host facility. 

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ROW Pipelines: 

Size Length Route Product Shut-in Time in 

the event of a 

leak

8.625” 143,800’ MC 657, 613, 612, 

568, 567, 523, 

522, 428, 477, 

476, 475, 474

Crude Within 60s

4.5” 23,200’ MC 475, 474 Gas Within 45s

6.625” 80’ MC 475 Gas Within 45s

6.625” 75’ MC 657 Crude Within 60s

8.625” 72’ MC 657 Crude Within 60s

8.625” 131’ MC 657 Crude Within 60s

8.625” 82’ MC 657 Crude Within 60s

6.625” 60’ MC 657 Crude Within 60s

13(b) Transportation System (existing) 

Oil Export 

The Na Kika Host oil export pipeline consists of an 18-inch diameter steel catenary riser and pipeline that 

terminates at Shell’s Main Pass 69 ‘P’ platform. The pipeline design pressure is 2600 psig and its 

maximum capacity is 140 MBOPD at a discharge pressure of 2400 psig and arrival pressure of 100 psig at 

MP 69 ‘P’. The pipeline maximum operating inlet temperature is 140° F.

Gas Export 

The gas export pipeline is part of the Okeanos pipeline system, which in turn is part or the Mardi Gras 

Transportation system. The pipeline departs Na Kika in a 20” diameter steel catenary riser, after the first 

5 miles the diameter increases to 24”. The total pipeline length is 74.8 miles and terminates at the Main 

Pass 260 Platform where it ties into the Destin gas pipeline system. The pipeline operating inlet 

temperature is 140° F. 

The Okaenos pipeline system has a design pressure of 3250 psig and a throughput capacity of over 1 

BCFD. 

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SECTION 14: SUPPORT VESSELS AND AIRCRAFT INFORMATION 

A. General 

Type Maximum Fuel Tank 

Storage Capacity

Maximum No. In Area at 

Any Time

Trip Frequency or 

Duration

Jumper Installation Vessel 9,000 bbls. 1 10 days 

Supply Boats 9,750 bbls. 1 Twice weekly

Stand by Vessel 500 bbls. 1 Daily

Crew Boats 1,040 bbls. 1 Twice Weekly

Helicopters 22 bbls. 2 10 per week

B. Diesel Oil Supply Vessels 

Size of Fuel Supply 

Vessel

Capacity of Fuel Supply 

Vessel

Frequency of Fuel 

Transfers

Route Fuel Supply Vessel Will 

Take

280 foot length 100,000 gals. 1 per week Port Fourchon to MC 657

C. Drilling Fluids Transportation 

According to NTL 2008-G04, this information in only required when activities are proposed in the 

State of Florida. 

D. Solid and Liquid Wastes Transportation 

See Section 7, Table 7B. 

E. Vicinity Map 

 See Attachment 14A for Vicinity Map. 

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Attachment 14A – Vicinity Map 

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SECTION 15: ONSHORE SUPPORT FACILITIES INFORMATION 

A. General 

Name Location Existing/New/Modified

C Port Port Fourchon, LA Existing

Amelia PHI Heliport Amelia, LA Existing

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

Boothville and Fourchon, Louisiana. The Fourchon boat facility is operated by Shell and is located 

on Bayou Lafourche, south of Leeville, LA approximately 3 miles from the Gulf of Mexico. The 

existing onshore air support base in Amelia, LA is located at 4008 Lake Palourde Road, Amelia, LA 

70340. 

B. Support Base Construction or Expansion 

This project will not cause support base construction or expansion. 

C. Support Base Construction or Expansion Timetable 

Based on B above, this is not applicable to this Plan. 

D. Waste Disposal 

See Section 7, Table 7B. 

SECTION 16: SULPHUR OPERATIONS INFORMATION 

Information regarding Sulfur Operations Information is not included in this plan as we are not proposing 

sulphur operations.

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SECTION 17: COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION 

Louisiana coastal zone consistancy was obtained in 2002 in plan N-07524 for this lease and is not 

required for supplemental plans. 

Alabama coastal zone consistancy is required for supplemental plans and is included in this section. 

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ALABAMA 

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

SUPPLEMENTAL DOCD 

Type of Plan 

 

MISSISSIPPI CANYON BLOCK 657

 Area and Blocks 

OCS-G 8496

Lease Number 

The proposed activity complies with the enforceable policies of Alabama’s approved management program 

and will be conducted in a manner consistent with such program. 

SHELL OFFSHORE INC.

Operator 

____________________________________________ 

Sylvia Bellone 

Certifying Official 

 04/17/2014 

Date 

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Coastal Zone Management Consistency Information 

For the State of Alabama 

In accordance with 30 CFR 550.226, Shell is hereby providing the following information in support of 

Section 18 (Environmental Impact Analysis) of our Plan for this lease. 

The regulations found in 15 CFR 930.58 identifies necessary data and information to be furnished to the 

State agency. The information is as follows: 

 CONSISTENCY CERTIFICATION 

A Coastal Zone Consistency Certification for activities that affect the State of Alabama is 

provided in Section 17 of this plan. 

 OTHER INFORMATION 

(1) Shell shall utilize a shore base in Fourchon, Louisiana for water support and PHI’s Amelia 

terminal for air traffic for the proposed activities. 

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

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

of this EP. 

 Oil Spill Information is provided in Section 9 of this plan. 

 All operations are covered by Shell’s Regional OSRP, which has approved by BOEM April 

2013. The Plan is available upon request. 

(3) Following is an evaluation that includes findings relating the coastal effects of the 

proposed activities and associated facilities to the relevant enforceable policies of the 

Alabama’s Coastal Management Program:

 

All activities shall be consistent with Alabama’s coastal management program and shall 

comply with all relevant rules and regulations. Pollution shall be prevented or reduced at the 

source; pollution that cannot be prevented shall be recycled in an environmentally safe 

manner; pollution that cannot be prevented or recycled shall be treated in an 

environmentally safe manner; and disposal or other release into the environment shall be 

employed only as a last resort and should be conducted in an environmentally safe manner. 

All activities comply with all applicable provisions of the administrative code. No activities are 

planned within special management areas. Activities will be carried out avoid unnecessary 

conflicts with other uses of the vicinity. 

COASTAL RESOURCE USE POLICIES 

Coastal Development – All activities shall be conducted in a manner that minimizes significant 

impacts to coastal resources. No adverse effects to Alabama’s coastal area are expected in

association with the proposed activities. 

 

Mineral Resource Exploration and Extraction – No conflicts with any other mineral resource 

exploration and extraction are expected. 

Commercial Fishing – All uses and activities shall be planned, sited, designed, constructed, 

operated and maintained to avoid to the maximum extent practicable adverse disruptions to 

fishery migratory patterns. 

Hazard Management- Effective emergency plans are in place, practiced and updated as 

necessary. The best practical techniques shall be utilized to prevent the release of pollutants 

or toxic substances into the environment.

Shoreline Erosion - All uses and activities shall be planned, sited, designed, constructed 

operated and maintained to avoid to the maximum extent practicable adverse alteration of 

protective coastal features 

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Recreation – We have considered the general factors utilized by permitting authorities and 

have determined that the proposed activities shall cause no adverse impacts on areas of 

public use or concern and all uses and activities shall be planned, sited, designed, 

constructed operated and maintained to avoid to the maximum extent practicable adverse 

alteration of these areas. BOEM has regulations in place which explicitly prohibit the disposal 

of equipment, cables, chains, chains, containers or other materials which may pose an 

unreasonable risk to public health, property, aquatic life, wildlife, recreation, navigation, 

commercial fishing, or other uses of the ocean into offshore waters. Although marine debris 

gets lost from time to time, the impact on Gulf Coast recreational beaches is expected to be 

minimal. No impacts are expected to adversely affect Public access to tidal and submerged 

lands, navigable waters and beaches or other public recreational resources. 

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

shore bases in Fourchon and Amelia, Louisiana will be utilized for the proposed operations. 

Also, boats will not travel through any sensitive coastal areas off of the coast of Alabama. 

NATURAL RESOURCE PROTECTION POLICIES 

Biological Productivity - All uses and activities shall be planned, sited, designed, constructed, 

operated and maintained to avoid to the maximum extent practicable adverse alteration of 

biologically valuable areas. All uses and activities shall be planned, sited, designed, 

constructed, operated and maintained to avoid to the maximum extent practicable reductions 

in long-term biological productivity of the coastal ecosystem. No impacts are expected to 

adversely affect the biological productivity of the area. 

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

water quality laws, standards and regulations. All discharges shall be covered by an NPDES 

permit. There shall be no discharge of untreated produced water, drilling muds, or cuttings 

resulting from energy exploration and production activities to the coastal waters of Alabama. 

Produced waters that are discharged offshore are diluted and dispersed to very near 

background levels at a distance of 1,000 m and are undetectable at a distance of 3,000 m 

from the discharge point. The BOEM regulations, the USEPA’s NPDES general permit and the 

USCG regulations implementing MARPOL 73/78 Annex V prohibit the disposal of any trash 

and debris into the marine environment. 

Water Resources - All uses and activities shall be planned, sited, designed, constructed, 

operated and maintained to avoid to the maximum extent practicable detrimental discharges 

into coastal waters. 

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

quality laws, standards and regulations. Emissions from the proposed activities are not 

expected to have significant impacts on onshore air quality because of the prevailing 

atmospheric conditions, emission heights, emission rates and the distance of these emissions 

from the coastline. 

Wetlands and Submerged Grass beds - All uses and activities shall be planned, sited, 

designed, constructed operated and maintained to avoid to the maximum extent practicable 

reductions of natural circulation patterns within or into wetlands and submerged grass beds. 

Pipeline and navigation canals are considered the most significant impacting factors to 

wetlands and neither is proposed in the plan. Proposed activities are not expected to have 

any adverse impact on sea grass communities. 

Beach and Dune Protection - Effective environmental protection plans are in place, practiced 

and updated as necessary. No significant impacts to the physical shape and structure of 

barrier beaches and associated dunes are expected to occur. In the unlikely event of a spill 

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

Wildlife Habitat Protection - We have considered the general factors utilized by permitting 

authorities and have determined that the proposed activities shall cause no adverse impacts 

on wildlife habitat areas. All uses and activities shall be planned, sited, designed, 

constructed, operated and maintained to avoid to the maximum extent practicable adverse 

alteration of wildlife habitats or coastal wildlife. Proposed activities are in OCS waters, so 

Page 100 Public Information Copy
they are located away from critical wildlife and vegetation areas. Access routes from shore 

base operations shall pose no adverse impacts on these critical wildlife and vegetation areas. 

Endangered Species 

No impacts are expected to adversely affect wildlife and fishery habitat, especially the 

designated Critical Habitats of Endangered Species. 

Beach mice – Potential impacts include oil spills, oil-spill response activities, consumption of 

beach trash and debris and coastal habitat degradation. No significant impacts to beach 

mice are expected to occur. Protective measures required under the Endangered Species Act 

should prevent any oil-spill response and cleanup activities from having significant impact to 

beach mice and their habitat. 

Marine birds– Potential impact-producing factors for marine birds in the offshore environment 

include helicopter and service vessel traffic and noise, air emissions, degradation of water 

quality, habitat degradation and ingestion discarded trash and debris from service vessels 

and OCS structures. Adverse impacts to endangered coastal and marine birds are expected 

to be sublethal. 

Sea turtles – Potential impact-producing factors from the proposed activities that may affect 

sea turtles include water quality degradation from operational discharges, noise from 

helicopter and vessel traffic and operating platforms, vessel collisions, brightly lit platforms 

and swallowing or getting tangled in OCS-related trash and debris. Routine activities are 

expected to be sublethal and unlikely to have significant adverse effects on the size and 

recovery of any sea turtle species or population in the Gulf of Mexico. 

Sturgeon – Drilling mud discharges may contain chemicals toxic to sturgeon, at 

concentrations four or five orders of magnitude higher than concentrations found a few 

meters from the discharge point. These discharges dilute to background levels within 1000m 

of the discharge point. No impacts from the proposed activities are expected. 

Cultural Resources Protection - All uses and activities shall be planned, sited, designed, 

constructed, operated and maintained to avoid to the maximum extent practicable adverse 

alteration of cultural resources. No impacts are expected to adversely affect historical, 

architectural, or archaeological sites. Should any historical, architectural, or archaeological 

resource be discovered in the course of conducting authorized activities, the Alabama 

Department of Environmental Management and the Alabama State Historical Officer shall be 

notified. 

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SECTION 18: ENVIRONMENTAL IMPACT ANALYSIS (EIA)

Environmental Impact Analysis 

SUPPLEMENTAL DEVELOPMENT OPERATIONS COORDINATION DOCUMENT 

Mississippi Canyon Block 657 (OCS-G 09496) 

Offshore Louisiana 

January 2014 

Prepared for: 

Shell Offshore Inc. 

P.O. Box 61933 

New Orleans, Louisiana 70161 

Telephone: (504) 425-6021 

Prepared by: 

CSA Ocean Sciences Inc. 

8502 SW Kansas Avenue 

Stuart, Florida 34997 

Telephone: (772) 219-3000 

Page 102 Public Information Copy
Introduction 

Project Summary

Shell Offshore Inc. (Shell) is submitting a Supplemental Development Operations Coordination 

Document (DOCD) for Mississippi Canyon (MC) Block 657 (MC 657) that includes the drilling and 

completion of the C-4 and C-5 wells, and installation of subsea production flowlines, jumpers, 

and umbilicals. 

Under this DOCD, Shell plans to drill, complete, and produce from two subsea wells: C-4 and C-5. 

The surface locations are in MC 657. New wellheads, trees, and jumpers and flying leads will be 

installed to facilitate production from the new wells to the existing Na Kika semisubmersible host 

facility. The activities discussed in this DOCD will use existing riser baskets and I-tubes on the Na 

Kika host facility. A new inlet separator, flowline heater, and chemical injection support facilities 

will be installed on the Na Kika host facility to accommodate production from the C-4 and 

C-5 wells. Equipment related to the Na Kika facility is not discussed further. 

The lease area is 84 miles (135 km) from the nearest shoreline, 151 miles (243 km) from the 

onshore support base at Port Fourchon, Louisiana, and 212 miles (341 km) from the helicopter 

base at Amelia, Louisiana. All miles in this Environmental Impact Analysis (EIA) are statute 

miles. Water depth at the wellsites is approximately 7,553 ft (2,302 m).

The following types of drilling rigs are available for this project: 

Transocean Deepwater Nautilus or a similar moored semisubmersible rig; 

Noble Don Taylor or a similar drillship; and 

 Noble Jim Day or a similar DP semisubmersible rig. 

The EIA is structured to address environmental impacts from all three types of drilling activity. 

Spudding for the proposed wells is scheduled for February 2015, with an estimated timeline of 

155 days per well for drilling and completion. 

Purpose of the EIA

This EIA was prepared pursuant to the requirements of the Outer Continental Shelf Lands Act 

(OCSLA), 43 U.S.C. §§ 1331-1356, as well as regulations including 30 CFR 550.242(s) and 

550.261. The EIA is a project- and site-specific analysis of Shell’s planned activities under this 

DOCD that focuses on the impacts of this specific plan.1 The EIA presents data, analyses, and 

conclusions to support BOEM reviews as required by the National Environmental Policy Act 

(NEPA) and other relevant federal laws, including the Endangered Species Act (ESA) and Marine 

Mammal Protection Act (MMPA). It also identifies some of the mitigation measures Shell will 

implement in connection with the planned activities. 

 

1

 On October 1, 2011, the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) 

reorganized into two separate agencies: Bureau of Ocean Energy Management (BOEM) and Bureau of Safety and 

Environmental Enforcement (BSEE). Shell understands that BOEM will review this EIA and prepare a Site-Specific 

Environmental Assessment (SEA) for the project. This EIA complies with guidance provided in existing Notices to 

Lessees and Operators (NTLs) issued by the former Minerals Management Service (MMS) and BOEMRE, including 

NTL 2008-G04 (recently extended by NTL 2014-G03). Throughout this EIA, when existing guidance and general 

agency activities are referred to, “BOEM” is meant to subsume the former agencies and to represent the 

continuous regulatory entity now called BOEM. The former agency names (MMS and BOEMRE) are used when 

referring to particular historical documents published under those names. In addition, until NTLs are reissued 

under BOEM or BSEE, the EIA will refer to the former BOEMRE as BOEM when addressing NTLs issued by BOEMRE 

or MMS. 

Page 103 Public Information Copy
This EIA addresses the impact-producing factors (IPFs), resources, and impacts associated with 

the activities proposed in this DOCD. The EIA also analyzes the potential environmental impacts 

of the revised blowout scenario and worst case discharge (WCD) information. 

BOEM has performed numerous environmental evaluations of oil and gas activities on the Gulf of 

Mexico Outer Continental Shelf (OCS). Potential impacts were analyzed at a broader level in the 

Programmatic Environmental Impact Statements (EISs) for the OCS Oil and Gas Leasing Program 

(MMS, 2007a; BOEM, 2012a) and in multi-lease-sale EISs for the Western and Central Gulf of 

Mexico Planning Areas (MMS, 2007b; BOEM, 2012b,c, 2013). The analyses from these documents 

are incorporated here by reference. These studies generated critical data and advanced the 

large body of existing knowledge on the Gulf of Mexico OCS. They analyze potential impacts on 

the natural environment, the socioeconomic effects of exploration and development activities, 

and other regional resources. Numerous technical studies address the likely trajectory of spilled 

oil, the effects of underwater noise on threatened and endangered species, and other IPFs. The 

studies inform agency decision-making on lease offerings, mitigation measures and lease 

stipulations, operational requirements, and permit restrictions. This substantial body of work 

which, in part, forms the basis for the evaluation presented here, will allow BOEM and other 

regulatory agencies to evaluate Shell’s DOCD and ensure that oil and gas exploration and 

development activities are performed in an environmentally sound manner, with minimal impacts 

on the environment. Shell has incorporated these comprehensive environmental analyses by 

reference and built on them with project- and site-specific analyses, where applicable. 

OCS Regulatory Framework

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

MMS (2010) and BOEM (2012b). Under the OCSLA, the U.S. Department of the Interior (USDOI) 

is responsible for the administration of mineral exploration and development of the OCS. Within 

the USDOI, BOEM and BSEE are charged with the responsibility of managing and regulating the 

development of OCS oil and gas resources in accordance with the provisions of the OCSLA. The 

BSEE offshore regulations are in 30 CFR Chapter II, Subchapter B. BOEM offshore regulations 

are in 30 CFR Chapter V, Subchapter B. 

In implementing its responsibilities under the OCSLA and NEPA, BOEM consults numerous federal 

departments and agencies that have authority to govern and maintain ocean resources pursuant 

to other federal laws. Among these are the U.S. Coast Guard (USCG), U.S. Environmental 

Protection Agency (USEPA), U.S. Fish and Wildlife Service (USFWS), and the National Oceanic 

and Atmospheric Administration (NOAA) through the National Marine Fisheries Service (NMFS). 

Federal regulations establish consultation and coordination processes with federal, state, and 

local agencies (e.g., the ESA, MMPA, Coastal Zone Management Act of 1972, and MagnusonStevens Fishery Conservation and Management Act). 

NTLs are formal documents issued by BOEM and BSEE that provide clarification, description, or 

interpretation of a regulation or standard. Table 1 lists and summarizes the NTLs applicable to 

this EIA.

Table 1. Notices to Lessees and Operators (NTLs) that are applicable to this Environmental 

Impact Analysis (EIA). 

NTL Title Summary

2014-G03 Extension of Prior Notices to 

Lessees

Extends the effective date of NTL 2008-G04 (and two other NTLs) 

until June 30, 2014.

2012-N06

Guidance to Owners and Operators 

of Offshore Facilities Seaward of 

the Coast Line Concerning 

Regional Oil Spill Response Plans

Provides clarification, guidance, and information for preparation of 

regional Oil Spill Response Plans. Recommends description of 

response strategy for worst case discharge (WCD) scenarios to 

ensure capability to respond to oil discharges is both efficient and 

effective.

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Table 1. (Continued). 

NTL Title Summary

2012-JOINT-G01

Vessel Strike Avoidance and 

Injured/Dead Protected Species 

Reporting

Recommends protected species identification training; recommends 

that vessel operators and crews maintain a vigilant watch for marine 

mammals and slow down or stop their vessel to avoid striking 

protected species; and requires operators to report sightings of any 

injured or dead protected species.

2012-BSEE-G01 Marine Trash and Debris 

Awareness and Elimination

Instructs operators to exercise caution in the handling and disposal 

of small items and packaging materials; requires the posting of 

placards at prominent locations on offshore vessels and structures; 

and mandates a yearly marine trash and debris awareness training 

and certification process.

2011-JOINT-G01

Revisions to the List of OCS 

Blocks Requiring Archaeological 

Resource Surveys and Reports

Provides new information on which Outer Continental Shelf (OCS) 

blocks require archaeological surveys and reports and line spacing 

required in each block. This NTL augments NTL 2005-G07.

2010-N10

Statement of Compliance with 

Applicable Regulations and 

Evaluation of Information 

Demonstrating Adequate Spill 

Response and Well Containment 

Resources

Informs operators using subsea blowout preventers (BOPs) or 

surface BOPs on floating facilities that applications for well permits 

must include a statement signed by an authorized company official 

stating that the operator will conduct all activities in compliance 

with all applicable regulations, including the increased safety 

measures regulations (75 FR 63346). Informs operators that BOEM 

will be evaluating whether each operator has submitted adequate 

information demonstrating that it has access to and can deploy 

containment resources to promptly respond to a blowout or other 

loss of well control.

2010-N06

Information Requirements for 

Exploration Plans, Development 

and Production Plans, and 

Development Operations 

Coordination Documents on the 

OCS

Rescinds the limitations set forth in NTL 2008-G04 regarding a 

blowout scenario and worst case discharge (WCD) scenario, and 

provides guidance regarding the information required in blowout 

scenario and WCD scenario descriptions.

2009-G40 Deepwater Benthic Communities

Provides guidance for avoiding and protecting high-density 

deepwater benthic communities (including chemosynthetic and 

deepwater coral communities) from damage caused by OCS oil and 

gas activities in water depths greater than 984 ft (300 m). Prescribes 

separation distances of 2,000 ft (610 m) from each mud and cuttings 

discharge location and 250 ft (76 m) from all other seafloor 

disturbances.

2009-G39 Biologically Sensitive Underwater 

Features and Areas

Provides guidance for avoiding and protecting biologically sensitive 

features and areas (i.e., topographic features, pinnacles, low-relief 

live bottom areas, and other potentially sensitive biological features) 

when conducting OCS operations in water depths less than 984 ft 

(300 m) in the Gulf of Mexico.

2009-G06 Military Warning and Water Test 

Areas

Provides contact links to individual command headquarters for the 

military warning and water test areas in the Gulf of Mexico. Lease 

stipulations require lessees or designated operators to enter into an 

agreement with the appropriate individual military command 

headquarters concerning the control of electromagnetic emissions 

and use of boats and aircraft in the applicable warning area or water 

test area before commencing such traffic.

2008-G04

Information Requirements for 

Exploration Plans and 

Development Operations 

Coordination Documents

Provides guidance on the information requirements for OCS plans, 

including EIA requirements and information regarding compliance 

with the provisions of the Endangered Species Act and Marine 

Mammal Protection Act.

2005-G07 Archaeological Resource Surveys 

and Reports

Provides guidance on regulations regarding archaeological 

discoveries, specifies requirements for archaeological resource 

surveys and reports, and outlines options for protecting 

archaeological resources.

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Oil Spill Prevention and Contingency Planning

Shell submitted an update to the Gulf of Mexico Regional Oil Spill Response Plan (OSRP) to the 

BSEE as a fundamental component of the planned drilling program that certifies Shell’s capability 

to respond to the maximum extent practicable to a WCD (30 CFR 254.2). The OSRP 

demonstrates Shell’s capabilities to rapidly and effectively manage oil spills that may result from 

drilling operations. Despite the extremely low likelihood of a large oil spill occurring during the 

project, Shell has designed its response program based upon a regional capability of responding 

to a range of spill volumes that increase from small operational spills to a WCD from a well 

blowout. Shell’s program is intended to meet the response planning requirements of the relevant 

coastal states and federal oil spill planning regulations. The OSRP includes information regarding 

Shell’s regional oil spill organization and dedicated response assets, potential spill risks, and local 

environmental sensitivities. The OSRP presents specific information on the response program 

that includes a description of personnel and equipment mobilization, the incident management 

team organization, and the strategies and tactics used to implement effective and sustained spill 

containment and recovery operations. 

EIA Organization

The EIA is organized into Sections A through I corresponding to the information required by 

NTL 2008-G04, which provides guidance regarding information required by 30 CFR Part 550 for 

DOCDs. The main impact-related discussions are in Section A (Impact-Producing Factors) and 

Section C (Impact Analysis). 

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A. Impact-Producing Factors 

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

Form BOEM-142. An “X” indicates that an IPF could reasonably be expected to affect a certain 

resource, and a dash (--) indicates no impact or negligible impact. Where there may be an 

effect, an analysis is provided in Section C. Potential IPFs for the proposed activity are listed 

below and briefly discussed in the following subsections: 

Drilling rig presence (including noise and lights); 

Physical disturbance to the seafloor; 

Air pollutant emissions; 

Effluent discharges; 

Water intake; 

Onshore waste disposal; 

Marine debris; 

Support vessel and helicopter traffic; and 

Accidents. 

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

As described previously, the wells will be drilled and completed using the either a DP drillship, DP 

semisubmersible rig, or an anchored semisubmersible rig. The rig will be on site for an estimated 

155 days per well. Non-anchored vessels will be on site for jumper and flying lead installation for 

brief intervals. Offshore support vessels will be used during the drilling program and there will 

likely be at least one vessel in the field at all times. The physical presence of a drilling rig in the 

ocean can attract pelagic fishes and other marine life, as discussed in Section C.5.1. 

A semisubmersible rig maintains buoyancy using ballasted, watertight pontoons located below 

the sea surface. The operating deck is located above the tops of passing waves. Structural 

columns connect the pontoons and operating deck. When the rig moves its location, the 

pontoons are de-ballasted and facilitating its transit to the new location. When on site at a 

drilling location, DP Semi-submersible rigs and DP drillships use thrusters to hold or adjust its 

position whereas an anchored semisubmersible rig uses anchors to maintain position. 

The physical presence of a DP drillship, DP semisubmersible rig, or anchored semisubmersible rig 

in the ocean can attract pelagic fishes and other marine life, as discussed in Section C.5.1. 

Drilling vessels also maintain exterior lighting for working at night and navigational and aviation 

safety in accordance with federal regulations. Artificial lighting may attract and directly or 

indirectly impact natural resources, particularly birds, as discussed in Section C.4. 

Drilling operations produce noise that includes strong tonal components at low frequencies, 

including infrasonic frequencies in at least some cases (MMS, 2000). Drilling noise from 

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

10 to 500 Hz (Richardson et al., 1995). From a DP drillship, DP semisubmersible rig, or anchored 

semisubmersible rig, sound and vibration are transmitted to the water either through the air or 

the risers (MMS, 2000). According to Richardson et al. (1995), source levels for sound 

emanating from a semisubmersible can be expected to be approximately 154 dB (re 1 μPa at 1 

m), with most energy in the low-frequency bands. 

Drilling rigs also maintain exterior lighting for working at night as well as navigational and 

aviation safety in accordance with applicable federal regulations. 

Underwater marine sounds associated with drilling operations are not particularly intense and 

include strong tonal components at low frequencies (averaging 10 to 500 Hz) and infrasonic 

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frequencies in at least some cases (Richardson et al., 1995; MMS, 2000). From a drillship or 

semisubmersible, sound and vibration associated with drilling operations are transmitted to the 

water either through the air or the risers (MMS, 2000). Marine sounds emitted by drilling rigs 

were found to be dominated by a mix of tones believed to be related to the drill string rotation 

rate. When drilling, the drill string represents a long vertical sound source. The DP thrusters, 

utilized by DP drillships and DP semisubmersible rigs, add another component to the marine 

sound signature from a drillship or semisubmersible drilling rig. DP thrusters can produce 

intermittent or continuous marine sound that varies depending on thruster type, operating 

efficiency, ship size, engine load, duty cycle, and weather or current conditions. 

The response of marine mammals, sea turtles, and fishes to a perceived marine sound depends 

on a range of factors, including 1) the sound pressure level, frequency, duration, and novelty of 

the sound; 2) the physical and behavioral state of the animal at the time of perception; and 3) 

the ambient acoustic features of the environment (Hildebrand, 2004).

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Table 2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (--) = no impact or negligible 

impact.

Environmental Resources

Impact-producing Factors

Drilling Rig 

Presence (incl. 

noise & lights)

Physical 

Disturbance 

to Seafloor

Air 

Pollutant 

Emissions

Effluent 

Discharges

Water 

Intake

Onshore 

Waste 

Disposal

Marine 

Debris

Support 

Vessel/Helo 

Traffic

Accidents

Small Fuel 

Spill

Large Oil 

Spill

Physical/Chemical Environment

Air quality -- -- X -- -- -- -- -- X(6) X(6)

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

Seafloor Habitats and Biota

Soft bottom benthic communities -- X -- X -- -- -- -- -- X(6)

High-density deepwater benthic communities -- --(4) -- --(4) -- -- -- -- -- X(6)

Designated topographic features -- --(1) -- --(1) -- -- -- -- -- --

Pinnacle trend area live bottoms -- --(2) -- --(2) -- -- -- -- -- --

Eastern Gulf live bottoms -- --(3) -- --(3) -- -- -- -- -- --

Threatened, Endangered, and Protected Species and Critical Habitat

Sperm whale (endangered) X(8) -- -- -- -- -- -- X(8) X(6,8) X(6,8)

Florida manatee (endangered) -- -- -- -- -- -- -- X(8) -- X(6,8)

Endangered mysticete whales -- -- -- -- -- -- -- -- -- --

Non-endangered marine mammals (protected) X -- -- -- -- -- -- X X(6) X(6)

Sea turtles (endangered/threatened) X(8) -- -- -- -- -- -- X(8) X(6,8) X(6,8)

Piping Plover (threatened) -- -- -- -- -- -- -- -- -- X(6)

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

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

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

Coastal and Marine Birds

Marine and pelagic birds X -- -- -- -- -- -- X X(6) X(6)

Shorebirds and coastal nesting birds -- -- -- -- -- -- -- X -- X(6)

Fisheries Resources

Pelagic communities and ichthyoplankton X -- -- X X -- -- -- X(6) X(6)

Essential Fish Habitat X -- -- X X -- -- -- X(6) X(6)

Archaeological Resources

Shipwreck sites -- X(7) -- -- -- -- -- -- -- X(6)

Prehistoric archaeological sites -- X(7) -- -- -- -- -- -- -- X(6)

Coastal Habitats and Protected Areas

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

Wetlands and seagrass beds -- -- -- -- -- -- -- X -- X(6)

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

Socioeconomic and Other Resources

Recreational and commercial fishing X -- -- -- -- -- -- -- X(6) X(6)

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

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

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

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

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

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Table 2 Footnotes and Applicability: 

(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, platform site, or 

any anchors will be on the seafloor within the following: 

(a) 4-mi zone of the Flower Garden Banks, or the 3-mi zone of Stetson Bank; 

(b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) protected by the Topographic 

Features Stipulation attached to an Outer Continental Shelf (OCS) lease; 

(c) Essential Fish Habitat (EFH) criteria of 500 ft from any no-activity zone; or 

(d) Proximity of any submarine bank (500-ft buffer zone) with relief greater than 2 m that is not protected by 

the Topographic Features Stipulation attached to an OCS lease. 

 Not applicable. The lease is not within the given ranges (buffer zone) of any marine sanctuary, 

topographic feature, or no-activity zone. There are no submarine banks in the lease block. 

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom 

(Pinnacle Trend) Stipulation attached to an OCS lease. 

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

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

(Low-Relief) Stipulation attached to an OCS lease. 

 The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area. 

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

 No impacts on high-density deepwater benthic communities are anticipated because no features 

indicative of high-density chemosynthetic communities or coral communities are located within 2,000 ft 

(610 m) of mud or cuttings discharge locations or within the 15,000-ft generic anchor radius for the 

proposed wellsites. 

(5) Exploration or production activities where H2S concentrations greater than 500 ppm might be encountered. 

 DOCD Section 4 contains Shell’s request for classification as an area absent of H2S.

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you 

determine would impact these environmental resources. If the proposed action is located a sufficient distance 

from a resource that no impact would occur, the EIA can note that in a sentence or two. 

 Accidental hydrocarbon spills could affect the resources marked "X" in the matrix, and impacts are 

analyzed in Section C. 

(7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated 

by the BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such 

blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the 

proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would 

occur, the EIA can note that in a sentence or two. 

 The lease area is on the list of archaeology survey blocks (BOEM, 2012d). The geohazards and 

archaeological assessments indicated multiple sonar contacts in the lease area, including a previously 

identified shipwreck, possibly a historic wooden sailing vessel located approximately 8,900 ft (2,713 m) 

south of the proposed wellsites. Impacts from anchors will be unlikely due to a 2,000 ft (610 m) 

avoidance zone around the shipwreck site and the distance between the wreck and the proposed 

wellsites. 

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

or sea turtles or their critical habitats. 

 Impact-producing factors (IPFs) that may affect marine mammals or sea turtles include drilling rig 

presence and emissions, support vessel and helicopter traffic, and accidents. See Section C. 

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

 Not applicable. 

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A.2 Physical Disturbance to the Seafloor

As described previously, the wells will be drilled using the either a DP drillship, DP 

semisubmersible rig, or an anchored semisubmersible rig. Dynamically positioned 

semisubmersible rigs and drillships do not use anchors for station-keeping or stabilization during 

drilling operations. There will be minimal disturbance to the seafloor and soft bottom 

communities during positioning of the wellbore and blowout preventers. Physical disturbance of 

the seafloor will be limited to the proximal area where the wellbore penetrates the substrate, and 

where mud and drill cuttings will be deposited. 

If utilized, the anchored semisubmersible rig will be held in place by suction pile anchors that will 

be deployed within an anchor radius of 15,000 ft (with 1,000 ft buffer). Anchoring causes 

physical compaction of the seafloor beneath the anchor, and chains or lines can disturb the 

bottom as well as resuspend sediments as they move. A disturbed area on the seafloor called 

the “anchor sweep” forms by the swing arc of anchor lines scraping across the bottom within the 

range allowed by the anchoring system configuration (BOEMRE, 2011). Anchored 

semisubmersibles disturb approximately 2 to 3 ha (5 to 7 ac) of seafloor at each wellsite, 

depending on the number of anchors and their mooring configurations (MMS, 2007b). 

Non-anchored dynamically positioned (DP) vessels will be used for jumper and flying lead 

installation. There will be no anchoring impacts, but placement of the subsea equipment will 

directly disturb the seafloor. 

The activities covered under this DOCD include a single 8.625-in. outside diameter (OD) 

production flowline and a 4.5-ft OD Gas Lift Riser connected to the Na Kika host facility. The 

production flowline is 143,800 ft long with a riser based inline sled (for gas lift tie-in) and an 

inline sled (for well C-4 tie-in), and terminates at a Pipeline End Termination (PLET). The 

production flowline is connected to the Gas Lift Riser via an 80-ft long, 4.5-in OD jumper at the 

riser base gas-lift sled and connected to the new C-4 well via a 75-ft long, 6.625-in. OD well 

jumper. A 72-ft long, 8.625-in. OD flowline jumper connects the PLET to a new 131-ft long, 

8.625-in. OD truss jumper, which in turn connects to the existing CG-1 sled via an 82-ft long, 

8.625-in. OD flowline jumper. Additionally, a new 60-ft long, 6.625-in. OD well jumper will 

connect the existing C-2 well to the new truss jumper. The 4.5-in. OD Gas Lift Riser is 23,200 ft 

long and terminates at a riser based sled that is connected to the Production Flowline by the 

previously mentioned 80-ft long, 4.5-in. OD jumper via the riser based gas-lift sled. 

The Coulomb Phase 2 project also includes three new umbilicals in a single dynamic section plus 

two static sections to perform control functions and deliver chemicals to support the production 

operations of the subsea development. 

A.3 Air Pollutant Emissions

Estimates of air pollutant emissions are provided in DOCD Section 8. Offshore air pollutant 

emissions will result from operations of the drilling rig, installation vessels, as well as service 

vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. Primary 

air pollutants typically associated with OCS activities are suspended particulate matter (PM), 

sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCs), and carbon 

monoxide (CO). 

MC 657 is located west of 87.5° W longitude; thus, air quality is under BOEM jurisdiction as 

explained in NTL 2009-N11. The implementing regulations are provided in 30 CFR 550 Subpart 

C. The Air Quality Emissions Report (see DOCD Section 8) prepared in accordance with BOEM 

requirements shows that the projected emissions from emission sources associated with the 

proposed activities meet the BOEM exemption criteria and are therefore exempt from further air 

quality review pursuant to 30 CFR 550.303(d). Based on calculated emissions and the project 

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location relative to shore, it can be concluded that project emissions will not significantly affect 

onshore air quality for any of the criteria pollutants. No further analysis or control measures are 

required. 

A.4 Effluent Discharges

Effluent discharges from the drilling rigs are summarized in DOCD Section 7. Support vessel 

discharges are expected to be in accordance with USCG regulations and, as applicable, the 

National Pollutant Discharge Elimination System (NPDES) Vessel General Permit, and therefore 

are not expected to cause significant impacts on water quality. Discharges from the 

semisubmersible rig will be in compliance with and monitored as required by the NPDES permit 

(GMG290000). 

Water-based drilling muds and cuttings will be released at the seafloor during the initial well 

intervals before the marine riser is set that allows their return to the surface. Excess cement 

slurry will also 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 for drilling activities after the marine riser is 

installed, which allows recirculation of the SBM fluids and cuttings. Unused or residual SBM will 

be collected and transported to Port Fourchon, Louisiana, for recycling. SBM cuttings will be 

discharged overboard via a downpipe below the water surface, after treatment that complies with 

the NPDES permit limitations for SBM fluid retained on cuttings. The estimated volume of SBM 

cuttings to be discharged is provided in DOCD Section 7. 

Well treatment fluids, completion fluids, and workover fluids may be discharged overboard via a 

downpipe below the water surface, after treatment that complies with NPDES permit limitations 

for these fluids. Other effluent discharges expected to be in accordance with the NPDES permit 

may include excess cement, non-contact cooling water, treated sanitary and domestic wastes, 

deck drainage, desalination unit brine, uncontaminated fire water, and ballast water. Drilling rig 

and support vessel discharges are expected to be in accordance with NPDES permit and USCG 

regulations, as applicable, and therefore are not expected to cause significant impacts on water 

quality. 

A.5 Water Intake

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

including firewater and once-through non-contact cooling of machinery on the drilling rig 

(DOCD Table 7a).

Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, 

design, construction, and capacity of cooling water intake structures reflect the best technology 

available to minimize adverse environmental impact from impingement and entrainment of 

aquatic organisms. The current general NPDES Permit No. GMG290000 specifies requirements 

for new facilities for which construction was commenced after July 17, 2006, with a cooling water 

intake structure having a design intake capacity of greater than 2 million gallons of water per 

day, of which at least 25% is used for cooling purposes. 

The wells will be drilled using either the using the either a DP drillship, DP semisubmersible rig, 

or an anchored semisubmersible rig. If the drilling vessel selected for this project meets the 

described applicability for new facilities, the vessel’s water intakes are expected to be in 

compliance with the design, monitoring, and recordkeeping requirements of the NPDES permit. 

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A.6 Onshore Waste Disposal

Wastes generated during development activities are tabulated in DOCD Section 7. 

Non-hazardous trash and debris and non-recyclable waste will be transported to Republic/BFI 

landfill in Sorrento, Louisiana or to the parish landfill in Avondale, Louisiana. Recyclable trash 

and debris will be recycled at Omega Waste Management in Patterson, Louisiana, or at ARC of 

New Iberia, Louisiana. Hazardous waste such as paints, solvents, and unused chemicals will be 

disposed of at Safety Kleen Systems, Inc. in Denton, Texas. Used oil will be sent to Omega 

Waste Management in Patterson, Louisiana, or ARC of New Iberia, Louisiana for recycling. At the 

onshore facilities, wastes will be recycled or disposed of according to applicable regulations. 

A.7 Marine Debris

Trash and debris released into the marine environment can harm marine animals through 

entanglement and ingestion. Shell will adhere to the International Convention for the Prevention 

of Pollution from Ships (MARPOL 73/78) Annex V requirements, USEPA and USCG regulations, 

and BSEE regulations and NTLs regarding solid wastes. BSEE regulations at 30 CFR 250.300(a) 

and (b)(6) prohibit operators from deliberately discharging containers and other similar materials 

(e.g., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable 

identification markings on equipment, tools and containers (especially drums), and other 

material. USCG and USEPA regulations require operators to become proactive in avoiding 

accidental loss of solid waste items by developing waste management plans, posting 

informational placards, manifesting trash sent to shore, and using special precautions such as 

covering outside trash bins to prevent accidental loss of solid waste. Shell complies with NTL 

2012-BSEE-G01, which instructs operators to exercise caution in the handling and disposal of 

small items and packaging materials, requires the posting of placards at prominent locations on 

offshore vessels and structures, and mandates a yearly marine trash and debris awareness 

training and certification process. Shell’s compliance with applicable laws, regulations, and NTL 

2012-BSEE-G01 will avoid significant impacts on the environment. 

A.8 Support Vessel and Helicopter Traffic

Shell will use existing shore base facilities at Port Fourchon and Amelia, Louisiana, for onshore 

support for water and air transportation, respectively. No terminal expansion or construction is 

planned at either location. 

The supply base at Port Fourchon is operated by Shell and located on Bayou Lafourche, 

approximately 3 miles (5 km) from the Gulf of Mexico. There will likely be at least one support 

vessel in the field at all times during drilling activities, with as many as three boats per day 

present during well spudding. The support and supply vessels will normally move to the project 

area via the most direct route from the shore base. Helicopters transporting personnel and small 

supplies will normally take the most direct route of travel between the helicopter base and the 

lease area when air traffic and weather conditions permit. Helicopters typically maintain a 

minimum altitude of 700 ft (213 m) while in transit offshore, 1,000 ft (305 m) over unpopulated 

areas or across coastlines, and 2,000 ft (610 m) over populated areas and sensitive habitats such 

as wildlife refuges and park properties. Additional guidelines and regulations specify that 

helicopters maintain an altitude of 1,000 ft (305 m) within 300 ft (91 m) of marine mammals 

(BOEM, 2012a). 

Vessel noise is one of the main contributors to overall noise in the sea (National Research Council 

[NRC], 2003a; Jasny et al., 2005). Offshore supply and service vessels associated with the 

proposed project would contribute to the overall noise environment by transmitting noise through 

both air and water. Vessel noise is a combination of narrow-band (tonal) and broadband sound 

(Richardson et al., 1995). Tones typically dominate up to about 50 Hz, whereas broadband 

sounds may extend to 100 kHz. The primary sources of vessel noise are propeller cavitation, 

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propeller singing, and propulsion; other sources include auxiliary engine noise, flow noise from 

water dragging along the hull, and bubbles breaking in the vessel’s wake while moving through 

the water (Richardson et al., 1995). Propeller cavitation is usually the dominant underwater 

noise source. The intensity of noise from service vessels is roughly related to ship size and 

speed. Broadband source levels for smaller boats (a category that would include supply and 

other service vessels) are in the range of 150 to 170 dB re 1 μPa at 1 m (Richardson et al., 

1995). 

Helicopters used for offshore oil and gas operation support are a potential source of noise to the 

marine environment. Helicopter noise is generated from their jet turbine engines, airframe, and 

rotors. The dominant tones for helicopters are generally below 500 Hz (Richardson et al., 1995). 

Richardson et al. (1995) reported received sound pressure levels in water of 109 dB re 1 μPa 

from a Bell 212 helicopter flying at an altitude of 152 m (500 ft). Penetration of aircraft noise 

below the sea surface is greatest directly below the aircraft; at angles greater than 13 degrees 

from vertical, much of the sound is reflected from the sea surface and so does not penetrate into 

the water (Richardson et al., 1995). The duration of underwater sound from passing aircraft is 

much shorter in water than air; for example, a helicopter passing at an altitude of 152 m (500 ft) 

that is audible in air for 4 minutes may be detectable under water for only 38 seconds at 3 m 

(10 ft) depth and for 11 seconds at 18 m (59 ft) depth (Richardson et al., 1995). 

A.9 Accidents

A.9.1 Types of Accidents Evaluated

This EIA focuses on two types of potential accidents: 

a small fuel spill, which is the most likely type of spill during OCS development activities; and 

an oil spill resulting from an uncontrolled blowout. A blowout resulting in a large oil spill is an 

extremely rare event, and the probability of such an event will be minimized by Shell’s well 

control and blowout prevention measures detailed in DOCD Section 2j. 

The following subsections summarize assumptions about the sizes and fates of these spills as 

well as Shell’s spill response plans. Impacts are analyzed in Section C. 

Lease sale EISs (MMS, 2007b; BOEMRE, 2011; BOEM, 2012a,c) analyzed other types of accidents 

including: chemical spills, vessel collisions, and loss of well control. These accidents are 

discussed briefly in Section A.9.4. 

A.9.2 Small Fuel Spill

Spill Size. According to the analysis in BOEM (2012b), the most likely type of small spill 

(<1,000 barrels [bbl]) as a result of OCS activities is a minor diesel fuel spill. Historically, most 

diesel spills have been <1 bbl, and this size is predicted to be the most common in ongoing and 

future OCS activities in the Western and Central Gulf of Mexico Planning Areas (BOEM, 2012b). 

The median size for spills <1 bbl is <0.024 bbl, and the median size for spills of 1 to 10 bbl is 

3 bbl (BOEM, 2012b). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational 

experience suggests that the most likely cause of such a spill would be a hose rupture resulting 

in the loss of the contents of a fuel transfer hose, which is less than 3 bbl. 

Spill Fate. The fate of a small fuel spill in the lease area would depend on meteorological and 

oceanographic conditions at the time, as well as the effectiveness of spill response activities. 

However, given the open ocean location of the lease area, the duration of a small spill and the 

opportunity for impacts to occur would be very brief. 

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic 

hydrocarbons (PAHs), which are moderately volatile (National Research Council [NRC], 2003). 

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The constituents of these oils are light to intermediate in molecular weight and can be readily 

degraded by aerobic microbial oxidation. Diesel’s density is such that it will not sink to the 

seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this 

generally occurs only in coastal areas with high-suspended solids loads (NRC, 2003) and would 

not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. 

Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006). 

The fate of a small diesel fuel spill was estimated using NOAA’s Automated Data Inquiry for 

Oil Spills 2 (ADIOS2) 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 more than 90% of a small 

diesel spill would evaporate or naturally disperse within 24 hours. The area of the sea surface 

with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 5 ha) depending on sea state and 

weather conditions. 

The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill, 

indicate that a small fuel spill would not affect coastal or shoreline resources. The lease area is 

84 miles (135 km) from the nearest shoreline (Louisiana). Modeling results discussed below 

indicate that a large spill in the lease area would have a 5% probability of contacting the nearest 

Louisiana shoreline (Plaquemines Parish) within 10 days after a spill. Slicks from spills are 

expected to persist for relatively short periods of time ranging from minutes (<1 bbl) to hours 

(<10 bbl) to a few days (10 to 1,000 bbl) and rapidly spread out, evaporate, and disperse into 

the water column. Because of the distance of a potential small spill on the OCS and the lack of 

persistence, it is unlikely that they would make landfall prior to dissipation (BOEM, 2012b). 

Spill Response. In the unlikely event of a small fuel spill, response equipment and trained 

personnel would be available to ensure that spill effects are localized and would result only in 

short-term, localized environmental consequences. DOCD Section 9b provides a detailed 

discussion of Shell’s response to a spill.

A.9.3 Large Oil Spill

A large oil spill is an extremely rare event, and the probability of such an event will be minimized 

by Shell’s well control and blowout prevention measures detailed in DOCD Section 2j. Blowouts 

are rare events and most do not result in oil spills (BOEM, 2012a). 

Spill Size. Shell has calculated a WCD for this DOCD using the requirements prescribed by 

NTL 2010-N06. The WCD is 37,105 bbl for the first day with a 30-day average of 15,013 barrels 

of oil per day (BOPD). The detailed analysis of this calculation can be found in 

DOCD Section 2j. The WCD scenario for this DOCD, in terms of both initial and the sustained 

rates, has a low probability of being realized. Some of the factors that are likely to reduce rates 

and volumes, which are not included in the WCD calculation, are obstructions or equipment in 

the wellbore, well bridging, and early intervention such as containment. 

Shell has a robust system in place to prevent blowouts. Included in DOCD Sections 2j and 9b

is Shell’s response to NTL 2010-N06, which includes descriptions of measures to prevent a 

blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the 

event of a blowout. Shell will also comply with NTL 2010-N10 and the Final Drilling Safety Rule, 

which specify additional safety measures for OCS activities. 

Spill Trajectory. The fate of a large oil spill in the lease area would depend on meteorological 

and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a 

computer simulation of oil spill transport that uses realistic data for winds and currents to predict 

spill fate. The OSRA report by Ji et al. (2004) provides conditional contact probabilities for 

shoreline segments. 

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The results for Launch Area 59 (the launch area nearest to the lease area) are presented in 

Table 3. The model predicts no shoreline contacts within 3 days. After 10 days, two Louisiana 

parishes may be contacted. After 30 days, seven Louisiana parishes and two counties on the 

Florida Panhandle may be contacted. Plaquemines Parish, Louisiana has the greatest probability 

of shoreline contact, with a 5% and 11% chance within 10 and 30 days, respectively. 

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

(From: Ji et al., 2004). Values are conditional probabilities that a hypothetical spill in 

the lease area (represented by OSRA Launch Area 59) could contact shoreline 

segments within 3, 10, or 30 days. 

Shoreline Segment County or Parish and State Conditional Probability of Contacta

(%)

3 Days 10 Days 30 Days

C13 Cameron, LA -- -- 1

C14 Vermilion, LA -- -- 1

C17 Terrebonne, LA -- -- 2

C18 Lafourche, LA -- 1 2

C19 Jefferson, LA -- -- 1

C20 Plaquemines, LA -- 5 11

C21 St. Bernard, LA -- -- 2

C29 Walton, FL -- -- 1

C30 Bay, FL -- -- 1

a

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

occurred (-- indicates less than 0.5%). 

The OSRA model does not evaluate the fate of a spill over time periods longer than 30 days, nor 

does it predict the fate of a release that continues over a period of weeks or months. Also as 

noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition 

or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response 

activities. The model does not assume a particular spill size but has generally been used by 

BOEM to evaluate contact probabilities for spills greater than 1,000 bbl. 

Weathering. Following an oil spill, several physical, chemical, and biological processes, 

collectively called weathering, interact to change the physical and chemical properties of the oil, 

and thereby influence its harmful effects on marine organisms and ecosystems. The most 

important weathering processes include spreading, evaporation, dissolution, dispersion into the 

water column, formation of water-in-oil emulsions, photochemical oxidation, microbial 

degradation, adsorption to suspended PM, and stranding on shore or sedimentation to the 

seafloor (NRC, 2003). 

Weathering decreases the concentration of oil and produces changes in its chemical composition, 

physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are 

lost rapidly by evaporation and dissolution from the slick on the water surface. Evaporated 

hydrocarbons are rapidly degraded by sunlight. Biodegradation of oil on the water surface and in 

the water column by marine bacteria removes first the n-alkanes and then the light aromatics 

from the oil. Other petroleum components are biodegraded more slowly. Photo-oxidation 

attacks mainly the medium and high molecular weight PAHs in the oil on the water surface. 

Spill Response. Shell is a founding member of the Marine Well Containment Company (MWCC) 

and has access to an integrated subsea well control and containment system that can be rapidly 

deployed through the MWCC. The MWCC is a non-profit organization that assists with the subsea 

containment system during a response. The near-term containment response capability will be 

specifically addressed in Shell’s NTL 2010-N10 submission at the time an Application for Permit to 

Drill (APD) is submitted and will include equipment and services available to Shell through 

MWCC’s development of near-term capability and other industry sources. Shell is a member of 

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Clean Caribbean & Americas, Marine Spill Response Corporation, Clean Gulf Associates, and Oil 

Spill Response Limited, organizations that are committed to providing the resources necessary to 

respond to a spill as outlined in Shell’s OSRP.

Mechanical recovery capabilities are addressed in the OSRP. The mechanical recovery response 

equipment that could be mobilized to the spill location in normal and adverse weather conditions 

is included in the Offshore On-Water Recovery Activation List in the OSRP. 

Chemical dispersion capabilities are also readily available from resources identified in the 

OSRP. Available equipment for surface and subsea application of dispersants, response times, 

and support resources are identified in the OSRP. 

Open-water in situ burning may also be used as a response strategy, depending on the 

circumstances of the release. If appropriate conditions exist and approval from the Unified 

Command is received, one or multiple in situ burning task forces could be deployed offshore. 

See DOCD Section 9b for a detailed description of spill response measures. 

A.9.4 Other Accidents Not Analyzed in Detail

The lease sale EISs (BOEM, 2012b,c) discuss four other types of accidents: chemical spills, 

pipeline failures, vessel collisions, and loss of well control. These accidents are discussed briefly 

below. No hydrogen sulfide (H2S) is expected at this site, and no other site-specific issues have 

been identified for this DOCD. The analysis in the lease sale EIS for these topics is incorporated 

by reference. 

Chemical Spill. Chemicals are used in drilling and producing operations to achieve technical goals 

in the drilling process, improve the efficiency and safety of drilling, and protect associated 

equipment. Chemicals used during drilling include surfactants, bentonite clays, olefins, inorganic 

salts, glycols, polymers, barite, and calcium carbonate. Supplies are renewed on a regular basis 

by transfer in containers from supply boats (Boehm et al., 2001). In addition to chemicals used 

in drilling fluids, the following chemicals are likely to be used on the rig: ethylene glycol (blowout 

prevention control fluid, used in closed cooling loops for crane and main engines and brake 

coolers), cement (used to cement casing in place), solvents (used in painting operations), 

hydraulic fluids (used in cranes and other hydraulic rig equipment), lubricating oil and grease 

(used in reciprocating and electrical equipment), and sodium hypochlorite (dilute, used as 

laundry bleach and disinfectant). 

A study of environmental risks of chemical products used in OCS activities determined that only 

two chemicals could potentially affect the marine environment in the concentrations typically 

used: zinc bromide and ammonium chloride (Boehm et al., 2001). The project addressed by this 

DOCD does not anticipate the use of either zinc bromide or ammonium chloride. Most other 

chemicals are either nontoxic or used in small quantities (BOEM, 2012b,c). No significant impacts 

are expected from chemical spills. 

Vessel Collisions. As summarized in MMS (2007b) and BOEM (2012b,c), 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. Approximately 10% of 

these collisions have caused spills of diesel fuel or chemicals (BOEM, 2012b,c). Shell will comply 

with USCG and BOEM-mandated safety requirements to minimize the potential for vessel 

collisions. 

Loss of Well Control. A loss of well control is the uncontrolled flow of a reservoir fluid that may 

result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is 

a broad term that includes minor to serious well control incidents, while blowouts are considered 

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to be a subset of more serious incidents with greater risk of oil spill or human injury (MMS, 

2007b). Loss of well control may result in the release of oil. Shell has a robust system in place 

to prevent loss of well control. Included in this DOCD is Shell’s response to NTL 2010-N06, which 

includes descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and 

conduct effective and early intervention in the event of a blowout. Shell will also comply with 

NTL 2010-N10 and the Final Drilling Safety Rule, which specify additional safety measures for 

OCS activities. See DOCD Sections 2j and 9b for further information. 

H2S Release. The lease area has been previously classified as H2S absent. 

B. Affected Environment 

The lease area is in the north-central Gulf of Mexico, 84 miles (135 km) from the nearest 

shoreline, 151 miles (243 km) from the onshore support base at Port Fourchon, Louisiana, and 

212 miles (341 km) from the helicopter base at Amelia, Louisiana. 

Water depth in MC 657 at the proposed C-4 and C-5 wellsites is approximately 7,553 ft (2,302 m) 

and there is no evidence of seafloor or near-surface faulting, slumping, amplitudes, or fluid 

expulsion features within the 15,000 ft (4,572 m) generic anchor radius for the proposed 

wellsites (McClelland Engineers, 1986; C&C Technologies, Inc., 2007). The side-scan sonar 

survey (C&C Technologies, Inc., 2006) identified no marine avoidance zones within 2,000 ft (610 

m) of the proposed wellsites. 

According to the survey results, the proposed wellsite locations appear suitable for the planned 

activities. 

A detailed description of the regional affected environment is provided in lease sale EISs 

(MMS, 2007b; BOEM, 2012b, 2012c, 2013), including meteorology, oceanography, geology, air 

and water quality, benthic communities, threatened and endangered species, biologically 

sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses. 

These regional descriptions are based on extensive literature reviews. These EISs 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 new information, if available. 

The local environment in the lease area is not known to be unique with respect to 

physical/chemical, biological, or socioeconomic conditions. Baseline environmental conditions in 

the lease area are expected to be consistent with the regional description of continental slope 

locations evaluated in MMS (2007b) and BOEM (2012b,c, 2013). 

C. Impact Analysis 

This section analyzes the potential direct and indirect impacts of routine activities and accidents; 

cumulative impacts are discussed in Section C.9. 

Impacts have been analyzed extensively in lease sale EISs for the Western and Central Gulf of 

Mexico Planning Areas (MMS, 2007b; BOEM, 2012b,c, 2013). Site-specific issues are addressed 

in this section as appropriate. 

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C.1 Physical/Chemical Environment

C.1.1 Air Quality

Due to the distance from shore-based pollution sources, offshore air quality is expected to be 

good. The attainment status of Federal OCS waters is unclassified because there is no provision 

in the Clean Air Act for classification of areas outside state waters (MMS, 2007b). 

In general, ambient air quality in coastal counties and parishes along the Gulf of Mexico is 

relatively good (BOEM, 2012a). As of December 5, 2013, Louisiana, Mississippi, and Alabama 

coastal counties and parishes are in attainment of the National Ambient Air Quality Standards 

(NAAQS) for all criteria pollutants (USEPA, 2013). One coastal metropolitan area in Texas 

(Houston-Galveston-Brazoria) is a nonattainment area for 8-hour ozone. One coastal 

metropolitan area in Florida (Tampa) is a nonattainment area for lead 2008 Standard. 

Winds in the region are driven by the clockwise circulation around the Bermuda High 

(MMS, 2007b). The Gulf of Mexico is located to the southwest of this center of circulation, 

resulting in a prevailing southeasterly to southerly flow, which is conducive to transporting 

emissions toward shore. However, circulation is also affected by tropical cyclones (hurricanes) 

during summer and fall and by extratropical cyclones (cold fronts) during winter. 

IPFs potentially affecting air quality are air pollutant emissions and two types of accidents: 

a small fuel spill and a large oil spill. 

Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant 

emissions will result from the operation of the drilling rig as well as helicopters and service 

vessels as described in Section A.3. These emissions occur mainly from combustion or burning 

of diesel fuel. Primary air pollutants typically associated with OCS activities are suspended PM, 

SOx, NOx, VOCs, and CO. 

Due to the distance from shore, routine operations in the project area are not expected to impact 

air quality along the coast. As noted in the lease sale EISs (MMS, 2007b; BOEM, 2012b,c, 2013), 

emissions of air pollutants from routine activities in the Gulf of Mexico Central Planning Area are 

projected to have minimal impacts on onshore air quality because of the prevailing atmospheric 

conditions, emission heights, emission rates, and the distance of these emissions from the 

coastline. 

MC 657 is located west of 87.5° W longitude; thus, air quality is under BOEM jurisdiction as 

explained in NTL 2009-N11. The BOEM implementing regulations are provided in 30 CFR 550 

Subpart C. The Air Quality Emissions Report (see DOCD Section 8) prepared in accordance 

with BOEM requirements shows that the projected emissions from emission sources associated 

with the proposed activities meet the BOEM exemption criteria. This DOCD is therefore exempt 

from further air quality review pursuant to 30 CFR 550.303(d). 

The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is 

designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air 

quality area. BOEM coordinates with the National Park Service (NPS) and the USFWS if emissions 

from proposed projects may affect the Breton Class I area. The lease area is approximately 

107 miles (172 km) from the Breton Wilderness Area. Shell will comply with emissions 

requirements as directed by BOEM. 

Carbon dioxide (CO2) and methane (CH4) emissions from the project would constitute a negligible 

contribution to greenhouse gas emissions from all OCS activities. According to Programmatic and 

OCS lease sale EISs (BOEM, 2012a,b), estimated CO2 emissions from OCS oil and gas sources are 

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0.4% of the U.S. total. OCS activities in the Central and Western Planning Areas contribute 

approximately 0.005% to total global CO2 emissions (BOEM, 2012b). Greenhouse gas emissions 

from the proposed project represent a negligible contribution to the total greenhouse gas 

emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not 

significantly alter any of the climate change impacts evaluated in the Programmatic EIS 

(BOEM, 2012a). 

Impacts of a Small Fuel Spill

Potential impacts of a small spill on air quality are expected to be consistent with those analyzed 

and discussed in previous EISs (MMS, 2007b; BOEM, 2012b,c, 2013). The probability of a small 

spill would be minimized by Shell’s preventative measures during routine operations, including 

fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and 

reduce the impacts. DOCD Section 9b provides detail on spill response measures. Given the 

open ocean location of the lease area, the extent and duration of air quality impacts from a small 

spill would not be significant. 

A small fuel spill would likely affect air quality near the spill site by introducing VOCs through 

evaporation. The ADIOS2 model (see Section A.9.2) indicates that more than 90% of a small 

diesel spill would evaporate or disperse within 24 hours. The area of the sea surface with diesel 

fuel on it would range from 1.2 to 12 ac (0.5 to 5 ha) depending on sea state and weather 

conditions. 

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

make landfall or reach coastal waters prior to breaking up (see Section A.9.2).

Impacts of a Large Oil Spill

Potential impacts of a large oil spill on air quality are expected to be consistent with those 

analyzed and discussed in previous EISs (MMS, 2007b; BOEM, 2012b,c, 2013). 

A large oil spill would likely affect air quality by introducing VOCs through evaporation from the 

slick. The extent and persistence of impacts would depend on the meteorological and 

oceanographic conditions at the time and the effectiveness of spill response measures. 

Additional air quality impacts could occur if response measures approved by the Unified 

Command included in situ burning of the floating oil. In situ burning would generate a plume of 

black smoke and result in emissions of NOx, SOx, CO, and PM, as well as greenhouse gases. 

Due to the lease area location (84 miles [135 km] from 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 air quality could also be affected. Based on the OSRA 

modeling predictions (Table 3), Plaquemines Parish, Louisiana is the coastal area most likely to 

be affected. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on air quality are expected. 

C.1.2 Water Quality

Deepwater areas in the Gulf of Mexico are relatively homogeneous with respect to temperature, 

salinity, and oxygen (BOEM, 2012c). IPFs potentially affecting water quality are effluent 

discharges and two types of accidents: a small fuel spill and a large oil spill. 

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Impacts of Effluent Discharges

Discharges of treated SBM cuttings will produce temporary, localized increases in suspended 

solids in the water column around the drilling rig. NPDES permit limits and requirements will be 

met. After discharge, SBM retained on cuttings would be expected to adhere tightly to the 

cuttings particles and, consequently, would not produce much turbidity as the cuttings sink 

through the water column (Neff et al., 2000). Recent EISs have concluded that the discharge of 

treated SBM cuttings will not cause persistent impacts on water quality in the lease area 

(BOEM, 2012b,c). 

Treated sanitary and domestic wastes may have a slight transient effect on water quality in the 

immediate vicinity of these discharges. NPDES permit limits and requirements will be met, and 

little or no impact on water quality is anticipated. 

Deck drainage includes effluents resulting from rain, deck washings, and runoff from curbs, 

gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated 

areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on 

the drilling rig deck and other areas such as chemical storage areas and places where equipment 

is exposed will be collected and oil and water separated to meet NPDES permit requirements. 

Negligible impact on water quality is anticipated. 

Other discharges from the semisubmersible rig expected to be in accordance with the NPDES 

permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast 

water, are expected to dilute rapidly and have little or no impact on water quality. 

Support vessels will discharge treated sanitary and domestic wastes. These will have a slight 

effect on water quality in the immediate vicinity of the discharges. Support vessel discharges are 

subject to USCG regulations and, as applicable, the NPDES Vessel General Permit, and therefore 

are not expected to cause significant impacts on water quality. 

Impacts of a Small Fuel Spill

Potential impacts of a small spill on water quality are expected to be consistent with those 

analyzed and discussed in previous EISs (MMS, 2007b; BOEM, 2012b,c, 2013). The probability of 

a small spill would be minimized by Shell’s preventative measures during routine operations, 

including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will 

mitigate and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Given the open ocean location of the lease area, the extent and duration of water quality impacts 

from a small spill would not be significant. 

A small fuel spill in offshore waters would increase the concentrations of petroleum hydrocarbons 

and their degradation products. The extent and persistence of impacts would depend on the 

meteorological and oceanographic conditions at the time and the effectiveness of spill response 

measures. However, it is estimated that more than 90% of a small diesel spill would evaporate 

or disperse within 24 hours (see Section A.9.2). The area of the sea surface with diesel fuel on 

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

The water-soluble fractions of diesel are dominated by two- and three-ringed PAHs, which are 

moderately volatile (NRC, 2003). The constituents of these oils are light to intermediate in 

molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel’s density is 

such that it will not sink and pool on the seafloor. Diesel dispersed in the water column can 

adhere to suspended sediments, but this generally occurs only in coastal areas with high 

suspended solid loads (NRC, 2003) and would not be expected to occur to any appreciable 

degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by 

naturally occurring microbes (NOAA, 2006). 

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

to make landfall or reach coastal waters prior to breaking up (see Section A.9.2).

Impacts of a Large Oil Spill

Potential impacts of a large oil spill on water quality are expected to be consistent with those 

analyzed and discussed in MMS (2007b) and BOEM (2012b,c, 2013). A large spill would likely 

affect water quality by producing a slick on the water surface and increasing the concentrations 

of petroleum hydrocarbons and their degradation products. The extent and persistence of 

impacts would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. Most of the oil would be expected to form a slick at the 

surface, although observations following the Macondo spill indicate that plumes of submerged oil 

droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 

2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). Recent analyses of the full set of 

samples associated with the Macondo spill have confirmed that the application of subsurface 

dispersants resulted in subsurface hydrocarbon plumes (Spier et al., 2013). Kujawinski et al. 

(2011) reported that chemical components of subsea dispersants used during the Macondo spill 

persisted for up to 2 months and were detectable up to 186 miles (300 km) from the wellsite at 

water depths of 3,280 to 3,937 ft (1,000 to 1,200 m). While dispersants were detectable in 353 

of the 4,114 total water samples, concentrations in the samples were significantly below the 

chronic screening level for dispersant (BOEM, 2012c). 

Once oil enters the ocean, a variety of physical, chemical, and biological processes act to disperse 

the oil slick. These processes include spreading, evaporation of the more volatile constituents, 

dissolution into the water column, emulsification of small droplets, agglomeration sinking, 

microbial modification, photochemical modification, and biological ingestion and excretion (NRC, 

2003). Marine water quality would be temporarily affected by the dissolved components and 

small oil droplets that do not rise to the surface or are mixed down by surface turbulence. 

Dispersion by currents and microbial degradation removes the oil from the water column or 

dilutes the constituents to background levels. 

A large oil spill could result in a release of gaseous hydrocarbons that could affect water quality. 

During the Macondo spill, large volumes of CH4 were released, causing localized oxygen depletion 

as methanotrophic bacteria rapidly metabolized the hydrocarbons (Joye et al., 2011; Kessler et 

al., 2011). However, a broader study of the deepwater Gulf of Mexico found that although some 

stations showed slight depression of dissolved oxygen concentrations relative to climatological 

background values, the findings were not indicative of hypoxia (<2.0 mg/L) (Operational Science 

Advisory Team [OSAT], 2010). Stations revisited around the Macondo wellhead in October 2010 

showed no measurable oxygen depressions (OSAT, 2010). 

Due to the lease area location (84 miles [135 km] from the nearest shoreline), most water quality 

impacts would occur in offshore waters. Depending on the spill trajectory and the effectiveness 

of spill response measures, coastal water quality could be affected. Based on the OSRA modeling 

predictions (Table 3), nearshore waters and embayments of Plaquemines Parish are the most 

likely coastal areas to be affected. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on water quality are expected. 

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C.2 Seafloor Habitats and Biota

Water depth at the proposed well surface locations is approximately 7,553 ft (2,302 m). See 

DOCD Section 6a for further information. 

According to BOEM (2012b,c), existing information for the deepwater Gulf of Mexico indicates 

that the seafloor is composed primarily of soft sediments; hard bottom communities are rare. In 

accordance with the guidance of NTL 2008-G04, a remotely operated vehicle (ROV) Monitoring 

Survey Plan is one of several requirements to accompany the DOCD when there is a potential to 

disturb seafloor areas in deepwater (>400 m). The specific requirements of the ROV Survey Plan 

are detailed in NTL 2008-G06. The BOEMRE (2011c) has subdivided the Gulf of Mexico Region 

(Western Planning Area, Central Planning Area, and parts of Eastern Planning Area) into grids. 

MC 657 is within deepwater Grid 17 where remotely operated vehicle (ROV) coverage of the 

seafloor is incomplete or considered inadequate to characterize the area (BOEM, 2010). 

Therefore, a plan for an ROV Monitoring Survey Plan is required pursuant to NTL 2008-G04. 

C.2.1 Soft Bottom Benthic Communities

Data from the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study 

(Wei, 2006; Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in 

the area. Table 4 summarizes data from two nearby stations in similar water depths. 

Sediments at these two stations were predominantly clay (51.1% [S36]; 56.9% [S37]) and silt 

(41.2% [S36]; 35.2% [S37]). 

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

sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic 

Ecology Study (From: Wei, 2006; Rowe and Kennicutt, 2009). 

Station

Location 

Relative to 

Lease Area

Water 

Depth (m)

Abundance

Meiofauna

(individuals/m2)

Macroinfauna

(individuals/m2)

Megafauna

(individuals/ha)

S36 42 mi NNE 1,839 799,963 4,481 359

S37 18 mi NE 2,382 291,179 1,445 1,451

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

Meiofauna (animals passing through a 0.5-mm sieve but retained on a 0.062-mm sieve) densities 

in water depths representative of the lease area typically range from approximately 

84,000 to 290,000 individuals/m2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and 

harpacticoid copepods were the three dominant groups in the meiofauna, accounting for 

approximately 90% of total abundance. 

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both 

of which are a reflection of the meager primary production in Gulf of Mexico surface waters (Wei, 

2006). Densities decrease exponentially with water depth. Based on an equation presented by 

Wei (2006), macroinfaunal densities in the water depth of the wellsites are expected to be 

approximately 2,800 individuals/m2, or lower than the values in Table 4. 

Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of Mexico 

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

four depth-dependent faunal zones (1 through 4), two of which are divided horizontally. The 

lease area is near the boundary of Zones 2E and 3E. Zone 2E consists of stations ranging in 

depth from 2,831 to 5,315 ft (625 to 1,828 m), covering the mid-Texas-Louisiana Slope, the west 

flank of the Mississippi Fan, the mid-Mississippi Canyon, the head of De Soto Canyon, and the 

mid-West Florida Terrace. Zone 3E encompasses the west flank of the lower Mississippi Fan, 

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lower Mississippi Canyon, lower DeSoto Canyon, lower West Florida Terrace, the deep Mississippi 

Fan, and the base of the Sigsbee Escarpment. The five most abundant species in Zone 2E were 

the polychaetes Litocorsa antennata, Aricidea suecica, Paralacydonia paradoxa, and Tharyx 

annulosus, and the bivalve Heterodonta sp D. The five most abundant species in Zone 3E were 

the polychaetes Paraonella monilaris and Tharyx marioni, the bivalves Heterodonta sp. B and 

Heterodonta sp. C, and the isopod Macrostylis sp. (Wei, 2006). 

Megafaunal density from nearby station S37 was 1,451 individuals/ha (Table 4). Densities of 

252 to 1,517 individuals/ha were reported from other stations in a similar depth range. Common 

megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal 

fishes, as well as sessile groups such as sponges and anemones. 

Bacteria are the foundation of deepsea chemosynthetic communities (Ross et al., 2012) and are 

an important component in terms of biomass and cycling of organic carbon (Cruz-Kaegi, 1998). 

Bacterial biomass at the depth range of the lease area typically is approximately 1 to 1.5 grams 

of carbon per square meter (g C/m2) in the top 6 inches (15 cm) of sediments (Rowe and 

Kennicutt, 2009). 

IPFs potentially affecting benthic communities are physical disturbance, effluent discharges 

(drilling mud and cuttings), and a large oil spill resulting from a well blowout at the seafloor. 

A small fuel spill would not affect benthic communities because the diesel fuel would float and 

dissipate on the sea surface. 

Impacts of Physical Disturbance to the Seafloor

The wells will be drilled using either a DP drillship, DP semisubmersible rig, or an anchored 

semisubmersible rig. 

In water depths such as those that are encountered in the lease area, dynamically positioned 

drilling semisubmersible rigs and drillships disturb the seafloor only around the wellbore (surface 

hole location) where the bottom template and blowout preventer are located. Depending upon 

the specific well configuration, this area is generally about 0.62 ac (0.25 ha) (BOEM, 2012b). 

The areal extent of these impacts from a dynamically positioned drilling rig will be small 

compared to the lease area itself. 

There will be minimal disturbance to soft bottom communities on the seafloor during positioning 

and anchoring of the anchored semisubmersible rig. Shell is proposing an anchor radius of 

10,000 ft (3,048 m) for each wellsite. Cables may initially be laid on the seafloor anywhere 

within the anchor radius. During anchor deployment, cables will rest on the seafloor only during 

the pre- and post-installation phase; once the rig arrives on location, cables will be pulled taut 

towards the rig. The cables will not sweep the seafloor or cross any sensitive features and 

therefore they are expected to have little physical impact on benthic communities. 

Anchoring causes physical compaction of the seafloor beneath the anchor, and chains or lines 

can disturb the bottom as well as resuspend sediments as they move. A disturbed area on the 

seafloor called the “anchor sweep” forms by the swing arc of anchor lines scraping across the 

bottom within the range allowed by the anchoring system configuration (BOEMRE, 2011). 

Anchored semisubmersibles disturb approximately 2 to 3 ha (5 to 7 ac) of seafloor at each 

wellsite, depending on the number of anchors and their mooring configurations (MMS, 2007b). 

The proximity of the two proposed wellsites may result in a smaller area of impact due to 

overlap. 

Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope 

(Gallaway et al., 2003; Rowe and Kennicutt, 2009). Small anchor and/or cable scars created 

during the project will likely remain on the bottom for months to years (Shinn et al., 1993). In a 

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study of drillsites on the Gulf of Mexico continental slope, Continental Shelf Associates, Inc. 

(2006) detected anchor scars up to 14 years after drilling was completed. These features will 

eventually disappear as sediments are redistributed by currents and benthic organisms. Physical 

disturbance to the seafloor during this project will have no significant impact on soft bottom 

benthic communities on a regional basis. 

Non-anchored DP vessels will be used for jumper and flying lead installation. There will be no 

anchoring impacts, but placement of the subsea equipment will directly disturb the seafloor. 

Impacts of Effluent Discharges

Drilling mud and cuttings are the only effluents likely to affect benthic communities. During 

initial well interval(s) before the marine riser is set, cuttings and seawater-based “spud mud” will 

be released at the seafloor. Excess cement slurry also will be released at the seafloor during 

casing installation for the riserless portion of the drilling operations. Cement slurry components 

typically include cement mix and some of the same chemicals used in water-based drilling mud 

(Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms 

within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by 

cuttings, drilling mud, and cement slurry will eventually be recolonized through larval settlement 

and migration from adjacent areas. Because some deepsea biota grow and reproduce slowly, 

recovery may require several years. 

Discharges of treated SBM cuttings from the rig may affect benthic communities, primarily within 

several hundred meters of the wellsites. The fate and effects of SBM cuttings have been 

reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico 

by Continental Shelf Associates, Inc. (2004, 2006). In general, cuttings with adhering SBM tend 

to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings 

deposition may develop elevated organic carbon concentrations and anoxic conditions 

(Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate and concentrations 

exceed approximately 1,000 mg/kg, benthic infaunal communities may be adversely affected due 

to both the toxicity of the base fluid and organic enrichment (with resulting anoxia) (Neff et al., 

2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that 

tolerate low oxygen and high H2S predominate (Continental Shelf Associates, Inc., 2006). As the 

base synthetic fluid is decomposed by microbes, the area will gradually return to pre-drilling 

conditions. Disturbed sediments will be recolonized through larval settlement and migration from 

adjacent areas. 

The areal extent of impacts from drilling discharges will be small; the typical effect radius is 

1,640 ft (500 m) around each wellsite. For the two surface locations in this development-drilling 

program, the total impact area would be 388 ac (157 ha). The overall impact area could be 

reduced due to the proximity of the proposed wells to each other. Soft bottom communities are 

ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 

2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have 

no significant impact on soft bottom benthic communities on a regional basis. 

Impacts of a Large Oil Spill

Potential impacts of a large oil spill on the benthic community are expected to be consistent with 

those analyzed and discussed in MMS (2007b) and BOEM (2012b,c). Likely impacts from a 

subsea blowout include smothering and exposure to toxic hydrocarbons from oiled sediment 

settling to the seafloor. The most likely effects of a subsea blowout on benthic communities 

would be within a few hundred meters of the wellsites. MMS (2007b) estimates that a severe 

subsurface blowout could resuspend and disperse sediments within a 984-ft (300-m) radius. 

While coarse sediments (sands) would probably settle at a rapid rate within 1,312 ft (400 m) 

from the blowout site, fine sediments (silts and clays) could be resuspended for more than 30 

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days and dispersed over a much wider area. Previous studies characterized surface sediments in 

the vicinity of the site as approximately 50% clay and 45% silt (Rowe and Kennicutt, 2009). 

Previous analyses (MMS, 2007a; BOEM, 2012b,d, 2013) concluded that oil spills would be unlikely 

to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical 

impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill 

location. However, during the Macondo spill, subsurface plumes were reported at a water depth 

of approximately 3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsite and 

persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently 

resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c; Spier et al., 

2013). Chemical components of subsea dispersants used during the Macondo spill persisted for 

up to two months and were detected 186 miles (300 km) from the wellsite in water depths of 

3,280 to 3,937 ft (1,000 to 1,200 m) (Kujawinski et al., 2011). However, estimated dispersant 

concentrations in the subsea plume were below levels known to be toxic to marine life. While 

the behavior and impacts of subsurface plumes are not well known, a subsurface plume could 

contact the seafloor and affect benthic communities beyond the 984-ft (300-m) radius estimated 

by MMS (2007a), depending on its extent, trajectory, and persistence. This contact could result 

in smothering of or toxicity to benthic organisms. The affected area would be recolonized by 

benthic organisms over a period of months to years (NRC, 2003). 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on soft bottom communities are expected. 

C.2.2 High-Density Deepwater Benthic Communities

As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas 

that could support chemosynthetic communities, deepwater corals, or other associated hard 

bottom communities. Chemosynthetic communities were discovered in the central Gulf of Mexico 

in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities 

are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007; 

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic 

carbonates created by chemosynthetic communities, and on shipwrecks. The nearest known 

chemosynthetic community site is located approximately 58 miles (93 km) north of the lease area 

in Viosca Knoll Block 826 (Brooks et al., 2009). Marmaduke & Associates, LLS (2005) and C&C 

Technologies, Inc. (2006) identified one historic shipwreck located approximately 8,900 ft (2,713 

m) to the south of the proposed wellsites. Because the wreck is buried in the sediment, it is 

unlikely that there is any hard bottom habitat available for colonization by deepwater corals. 

Details concerning the historic shipwreck are in Section C.6.1. 

The chemosynthetic community assessment by McClelland Engineers (1986) and 

C&C Technologies, Inc. (2007) did not identify features that could support high-density 

deepwater benthic communities within 2,000 ft (610 m) of the proposed wellsites or within the 

15,000-ft generic anchor radius for the proposed wellsites. 

IPFs potentially affecting high-density deepwater benthic communities are effluent discharges 

(drilling mud and cuttings), and a large oil spill from a well blowout at the seafloor. A small fuel 

spill would not affect benthic communities because the diesel fuel would float and dissipate on 

the sea surface. 

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Impacts of Effluent Discharges

The chemosynthetic community assessment included in this DOCD, based on the reports by 

McClelland Engineers (1986) and C&C Technologies, Inc. (2007), did not identify features that 

could support high-density deepwater benthic communities within 2,000 ft (610 m) of the 

proposed drilling mud/cuttings discharge locations. Monitoring programs on the Gulf of Mexico 

continental slope have shown that benthic impacts from drilling discharges typically are 

concentrated within approximately 1,640 ft (500 m) of the wellsites, although detectable deposits 

may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 

2005). 

Impacts of a Large Oil Spill

BOEM (2012a) concluded that oil spills would be unlikely to affect benthic communities beyond 

the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil 

would rise quickly to the sea surface directly over the spill location. However, during the 

Macondo spill, subsurface plumes were reported at a water depth of approximately 3,600 ft 

(1,100 m), extending at least 22 miles (35 km) from the wellsite and persisting for more than a 

month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of 

dispersants at the wellhead (Joint Analysis Group, 2010c). Chemical components of subsea 

dispersants used during the Macondo spill persisted for up to 2 months and were detectable 

186 miles (300 km) from the wellsite in water depths of 3,280 to 3,937 ft (1,000 to 1,200 m) 

(Kujawinski et al., 2011). However, estimated dispersant concentrations in the subsea plume 

were below levels known to be toxic to marine life. While the behavior and impacts of 

subsurface plumes are not well known, a subsurface plume could have the potential to contact 

high-density deepwater benthic communities beyond the 984-ft (300-m) radius estimated by 

MMS (2007a), depending on its extent, trajectory, and persistence. Potential impacts on 

sensitive resources would be an integral part of the decision and approval process for the use of 

dispersants. The chemosynthetic community assessment by McClelland Engineers (1986) and 

C&C Technologies, Inc. (2007) did not identify high-density deepwater benthic communities 

within 2,000 ft (610 m) of the proposed drilling mud/cuttings discharge locations. Potential 

impacts of oil on high-density deepwater benthic communities are discussed in MMS (2007b) and 

BOEM (2012b). 

Although chemosynthetic communities live among hydrocarbon seeps, natural seepage occurs at 

a relatively constant, low rate compared with the potential rates of oil release from a blowout. In 

addition, seep organisms require unrestricted access to oxygenated water at the same time as 

exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment 

particles could come into contact with chemosynthetic organisms or deepwater corals. As 

discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral 

coverage; destruction of hard substrate; change in sediment characteristics; and reduction or 

loss of one or more commercial and recreational fishery habitats. Sublethal effects could be long 

lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water 

temperature and diseases) (BOEM, 2012c). 

The potential for a spill to affect deepwater corals was observed during an October 2010 survey 

of deepwater coral habitats in a water depth of 4,600 ft (1,400 m) approximately 7 miles (11 km) 

southwest of the Macondo wellhead. Much of the soft coral observed in a location measuring 

approximately 50 by 130 ft (15 by 40 m) was covered by a brown flocculent material (BOEMRE, 

2010) with signs of stress, including varying degrees of tissue loss and excess mucous production 

(White et al., 2012). Researchers concluded, based on hopanoid petroleum biomarker analysis of 

the flocculent material, that it contained oil from the Macondo spill. The injured and dead corals 

were in an area where a subsea plume of oil had been documented during the spill in June 2010. 

The deepwater coral at this location showed signs of tissue damage that was not observed 

elsewhere during these surveys or in previous deepwater coral studies in the Gulf of Mexico. The 

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team of researchers concluded that the observed coral injuries likely resulted from exposure to 

the subsurface oil plume (White et al., 2012). 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Potential impacts on sensitive resources would be an integral part of the decision and approval 

process for the use of dispersants. Therefore, no significant spill impacts on deepwater benthic 

communities are expected. 

C.2.3 Designated Topographic Features

The lease blocks are not within or near a designated topographic feature or a no-activity zone as 

identified in NTL 2009-G39. The nearest designated topographic feature stipulation block is West 

Delta 147, located 98 miles (158 km) west-northwest of the lease area. 

There are no IPFs associated with either routine operations or accidents that could cause impacts 

to designated topographic features due to the distance from the lease area. 

C.2.4 Pinnacle Trend Area Live Bottoms

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

NTL 2009-G39, the nearest pinnacle trend blocks are located approximately 62 miles (100 km) 

north-northwest of the lease area in Viosca Knoll 778. 

There are no IPFs associated with either routine operations or accidents that could cause impacts 

to pinnacle trend area live bottoms due to the distance from the lease area. 

C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which applies to 

seagrass communities and low-relief hard bottom reef within the Gulf of Mexico Eastern Planning 

Area leases in water depths of 328 ft (100 m) or less and portions of Pensacola and Destin Dome 

Area Blocks in the Central Planning Area. The nearest blocks covered by the Live Bottom 

Stipulation, as defined by NTL 2009-G39, are approximately 73 miles (117 km) north of the 

project area in Destin Dome 573. 

There are no IPFs associated with either routine operations or accidents that could cause impacts 

to eastern Gulf live bottom areas due to the distance from the lease area. 

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

This section discusses species listed as endangered or threatened under the ESA. In addition, it 

includes all marine mammal species in the region, which are protected under the MMPA. 

Endangered or threatened species that may occur in the project area and along the northern Gulf 

Coast are listed in Table 5. The table also indicates the location of designated critical habitat in 

the Gulf of Mexico. Critical habitat is defined as (1) specific areas within the geographical area 

occupied by the species at the time of listing, if they contain physical or biological features 

essential to conservation, and those features may require special management considerations or 

protection; and (2) specific areas outside the geographical area occupied by the species if the 

agency determines that the area itself is essential for conservation. NMFS has jurisdiction over 

ESA-listed cetaceans and fishes in the Gulf of Mexico. The USFWS has jurisdiction over ESAlisted birds and the Florida manatee. These two agencies share federal jurisdiction over sea 

turtles, with NMFS having lead responsibility at sea and USFWS on nesting beaches. 

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The sperm whale and five species of sea turtles are the only endangered or threatened species 

likely to occur at or near the lease area. No critical habitat has been designated for these species 

in the Gulf of Mexico. 

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right 

whale, and sei whale) also have been reported in 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. 

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

Sei whale Balaenoptera borealis E X

a

-- None

Blue whale Balaenoptera musculus E X

a

-- None

Fin whale Balaenoptera physalus E X

a

-- None

North Atlantic right whale Eubalaena glacialis E X

a

-- None

Humpback whale Megaptera novaeangliae E X

a

-- None

Sperm whale Physeter macrocephalus E X -- None

Florida manatee Trichechus manatus 

latirostris E -- X

Florida 

(Peninsular)

Sea Turtles

Loggerhead turtle Caretta caretta T, Eb X X Proposedb

Green turtle Chelonia mydas T, Ec 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 mouse (subspecies: 

Alabama, Choctawhatchee, 

Perdido Key, St. Andrew)

Peromyscus polionotus E -- X

Alabama and Florida 

(Panhandle) beaches

Abbreviations: E = Endangered; T = Threatened. 

a The sei, blue, fin, North Atlantic right, and humpback whales are rare or extralimital in the Gulf of Mexico and are 

unlikely to be present in the lease area. 

b The loggerhead turtle is composed of nine distinct population segments (DPS) that are considered “species.” The 

only DPS that may occur in the project area (Northwest Atlantic DPS) is listed as threatened (76 FR 58868; 

September 22, 2011). The USFWS has proposed to designate critical habitat for this DPS, including beaches in 

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Jackson County, Mississippi; Baldwin County, Alabama; and Bay, Gulf, and Franklin Counties in the Florida 

Panhandle, as well as several counties in southwest Florida and the Florida Keys (78 FR 18000). 

c The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

Coastal endangered or threatened species include the Florida manatee, Piping Plover, 

Whooping Crane, Gulf sturgeon, and four subspecies of beach mouse. Critical habitat has been 

designated for all of these species as indicated in Table 5 and discussed in individual sections. 

Two other coastal species (Bald Eagle and Brown Pelican) discussed by MMS (2007b) and 

BOEM (2012b) are no longer listed as endangered or threatened; these species are discussed in 

Section C.4.2. 

There are no other endangered animals or plants in the Gulf of Mexico that are reasonably likely 

to be affected by either routine or accidental events. Other species occurring at certain locations 

in the Gulf of Mexico such as the smalltooth sawfish (Pristis pectinata), elkhorn coral (Acropora 

palmata), staghorn coral (Acropora cervicornis), and Florida salt marsh vole 

(Microtus pennsylvanicus dukecampbelli) are remote from the lease area and highly unlikely to be 

affected. 

C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the 

sperm whale (Physeter macrocephalus). Resident populations of sperm whales occur within the 

Gulf of Mexico. A species description is presented in a recent lease sale EIS (MMS, 2007b). 

Gulf of Mexico sperm whales are classified as an endangered species and a “strategic stock” 

(defined as a stock that may have unsustainable human-caused impacts) by NMFS (Waring et al., 

2012). No critical habitat for the sperm whale has been designated in the Gulf of Mexico. 

The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical 

features such as eddies associated with the Loop Current (Jochens et al., 2008). Sperm whale 

populations in the north-central Gulf of Mexico are present there throughout the year 

(Davis et al., 2000). Results of a multi-year tracking study show female sperm whales typically 

concentrated along the upper continental slope between the 656- and 3,280-ft (200- and 

1,000-m) depth contours (Jochens et al., 2008). Male sperm whales were more variable in their 

movements and were documented in water depths greater than 9,843 ft (3,000 m). Generally, 

groups of sperm whales sighted in the Gulf of Mexico during the MMS-funded Sperm Whale 

Seismic Study (SWSS) consisted of mixed-sex groups comprising adult females and immatures, 

and groups of bachelor males. Typical group size for mixed groups was 10 individuals 

(Jochens et al., 2008). A review of sighting reports from seismic mitigation surveys in the 

Gulf of Mexico conducted over a 6-year period found a mean group size for sperm whales of 

2.5 individuals (Barkaszi et al., 2012). 

In these mitigation surveys, sperm whales were the most common cetacean encountered 

(Barkaszi et al., 2012). SWSS results show that sperm whales transit through the vicinity of the 

lease area. Movements of satellite-tracked individuals suggest that this area of the Gulf 

continental slope is within the home range of the Gulf of Mexico population (within the 

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

Current threats to sperm whale populations worldwide are discussed in a final recovery plan for 

the sperm whale recently published by NOAA (NMFS, 2010a). Threats are defined as “any factor 

that could represent an impediment to recovery,” and include fisheries interactions, 

anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from 

marine debris, research, predation and natural mortality, direct harvest, competition for 

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resources, loss of prey base due to climate change and ecosystem change, and cable laying. 

In the Gulf of Mexico, the impacts from many of these threats are identified as either low or 

unknown (BOEMRE, 2011; BOEM, 2012c). 

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support 

vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill. 

Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, 

the small area of ocean affected, the intermittent nature of the discharges, and the mobility of 

these marine mammals. Compliance with NTL 2012-BSEE-G01 will minimize the potential for 

marine debris-related impacts on sperm whales. 

Impacts of Drilling Rig Presence, Noise, and Lights

Some sounds produced by the drilling rig may be emitted at levels that could potentially disturb 

individual whales or mask the sounds animals would normally produce or hear. Noise associated 

with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be 

transient. As discussed in Section A.1, the bandwidth of sounds generated by the drilling rig is 

approximately 100 to 500 Hz. 

Sperm whales appear to have good low-frequency hearing, with variable responses to 

anthropogenic noise (Jochens et al., 2008). The sperm whale may possess better low-frequency 

hearing than some of the other odontocetes (toothed whales and dolphins), although not as low 

as many mysticetes (baleen whales) that produce sounds within a bandwidth between 30 Hz and 

greater than 5 kHz (Wartzok and Ketten, 1999). Southall et al. (2007) lists sperm whales in the 

same hearing group (i.e., mid-frequency cetaceans) as dolphins, toothed whales, beaked whales, 

and bottlenose whales (estimated hearing range from 150 Hz to 160 kHz). Generally, most of 

the acoustic energy from sperm whales is present at frequencies below 4 kHz, although diffuse 

energy up to and over 20 kHz has been reported, with source levels up to 236 dB re 1 μPa at 

1 m. Other studies indicate sperm whales’ wideband clicks contain energy between 0.1 and 20 

kHz (Weilgart and Whitehead, 1993; Goold and Jones, 1995). Most observations of behavioral 

responses of marine mammals to anthropogenic sounds, in general, have been limited to shortterm behavioral responses, which included the cessation of feeding, resting, or social interactions 

(NMFS, 2009). 

Observations of sperm whales near offshore oil and gas operations suggest an inconsistent 

response to anthropogenic marine sound (Jochens et al., 2008). Sounds produced during drilling 

operations are generally constant (rather than pulsed or intermittent) and at levels that may be 

louder than, and of a similar frequency to, the auditory signal received by sperm whales. 

Animals can determine the direction from which a sound arrives based on cues, such as 

difference in arrival times, sound levels, and phases at the two ears. Thus, an animal’s 

directional hearing capabilities have a bearing on its vulnerability to masking (NRC, 2003). 

Behavioral changes for marine mammals such as the sperm whale to auditory masking sounds 

may include producing more calls, longer calls, or shifting the frequency of the calls 

(NMFS, 2009; Holt et al., 2009). 

In addition, there are other OCS facilities and activities near the lease area, and the region as a 

whole has a large number of similar sound sources. Drilling-related noise associated with this 

project will contribute to increases in the ambient noise environment of the Gulf of Mexico, but it 

is not expected in amplitudes sufficient enough to cause either hearing or behavioral effects to 

sperm whales. 

The drilling rig used during the proposed activity will be located within a deepwater, open ocean 

environment and will maintain position during drilling operations. Sounds generated by the rig 

and by drilling operations will be generally continuous with some variability in sound level. This 

analysis assumes that the continuous nature of sounds produced by the drilling rig will provide 

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individual whales with cues relative to the direction and relative distance (sound intensity) of the 

sound source, and the fixed position of the drilling rig will provide multiple options for active 

avoidance of potential physical impacts. 

NMFS analyzed the potential for impacts of drilling-related noise on sperm whales in its Biological 

Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas 

of the Gulf of Mexico (NMFS, 2007). The analysis noted that drilling rigs show low sound source 

levels and concluded that drilling is not expected to produce amplitudes sufficient to cause 

hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 

2007). 

Although offshore lighting and presence of drilling rigs and OCS vessels were considered potential 

factors affecting sperm whales, NMFS’s 2007 Biological Opinion and lease sale EISs (MMS, 

2007b; BOEM, 2012b,c, 2013) did not identify these as IPFs for sperm whales. Therefore, no 

significant impacts are expected. 

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales. There is also a risk of vessel 

strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a). Data 

concerning the frequency of vessel strikes are presented in the lease sale EIS (MMS, 2007b). 

To reduce the potential for vessel strikes, BOEM has issued NTL 2012-JOINT-G01, which 

recommends protected species identification training and that vessel operators and crews 

maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid 

striking protected species, and requires operators to report sightings of any injured or dead 

protected species. When whales are sighted, vessel operators and crews are required to attempt 

to maintain a distance of 300 ft (91 m) or greater whenever possible. Vessel operators are 

required to reduce vessel speed to 10 knots or less, when safety permits, when mother/calf pairs, 

pods, or large assemblages of cetaceans are observed near an underway vessel. Compliance 

with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for 

disturbing sperm whales. 

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales in its 

Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western 

Planning Areas of the Gulf of Mexico (NMFS, 2007). With implementation of the mitigation 

measures in NTL 2012-JOINT-G01, NMFS concluded that the likelihood of collisions between 

vessels and sperm whales would be reduced to insignificant levels. NMFS concluded that the 

observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a 

potential threat and is not expected to result in any significant effect on migration, breathing, 

nursing, breeding, feeding, or sheltering to individuals, or have any consequences at the level of 

the population. With implementation of the vessel strike avoidance measures requirement to 

maintain a distance of 295 ft (90 m) from sperm whales, NMFS concluded that the potential for 

harassment of sperm whales would be reduced to discountable levels. 

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) 

documented responses of sperm whales offshore Hawaii to fixed-wing aircraft flying at an 

altitude of 800 ft (245 m). A reaction to the initial pass of the aircraft was observed during three 

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

1,180 ft (360 m) lateral distance from the aircraft. Additional reactions were seen when aircraft 

circled certain whales to make further observations. Based on other studies of cetacean 

responses to sound, the authors concluded that the observed reactions to brief overflights by the 

aircraft were short-term and probably of no long-term biological significance. 

Helicopters maintain altitudes above 700 ft (213 m) during transit to and from the offshore 

working area. In the event that a whale is seen during transit, the helicopter will not approach 

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or circle the animal(s). In addition, guidelines and regulations specify that helicopters maintain 

an altitude of 1,000 ft (305 m) within 300 ft (91 m) of marine mammals (BOEM, 2012a,b). 

Although whales may respond to helicopters (Smultea et al., 2008), NMFS (2007) and 

BOEM (2012a) 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 MMS (2007b) 

and BOEM (2012b,c, 2013) and the Biological Opinion for the Five-Year Oil and Gas Leasing 

Program in the Central and Western Planning Areas of the Gulf of Mexico (NMFS, 2007). Oil 

impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this DOCD, there 

are no unique site-specific issues with respect to spill impacts on these animals. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts on sperm whales. DOCD Section 9b provides 

detail on spill response measures. Given the open ocean location of the lease area, the duration 

of a small spill and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that more than 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and 

noise of response vessels and aircraft (Marine Mammal Commission [MMC], 2011). However, 

due to the limited areal extent and short duration of water quality impacts from a small fuel spill, 

as well as the mobility of sperm whales, no significant impacts would be expected. 

Impacts of a Large Oil Spill

Potential spill impacts on marine mammals including sperm whales are discussed in 

MMS (2007b), NMFS (2007), and BOEM (2012a,b,d, 2013). Oil impacts on marine mammals are 

discussed by Geraci and St. Aubin (1990). For this DOCD, there are no unique site-specific issues 

with respect to spill impacts on these animals. 

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as 

indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and 

dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from 

the activities and noise of response vessels and aircraft. The level of impact of oil exposure 

depends on the amount, frequency, and duration of exposure; route of exposure; and type or 

condition of petroleum compounds or chemical dispersants (Waring et al., 2013). Complications 

of the above may lead to dysfunction of immune and reproductive systems, physiological stress, 

declining physical condition, and death. Behavioral responses can include displacement of 

animals from prime habitat, disruption of social structure, changing prey availability and foraging 

distribution and/or patterns, changing reproductive behavior/productivity, and changing 

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movement patterns or migration (MMC, 2011). Ackleh et al. (2012) hypothesized that sperm 

whales may have temporarily relocated away from areas near the Macondo spill in 2010. 

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury 

or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce 

the potential for striking or disturbing these animals. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on sperm whales are expected. 

C.3.2 Florida Manatee (Endangered)

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

Manatees regularly migrate farther west of Florida in the warmer months (Wilson, 2003) into 

Alabama and Louisiana coastal environs, with some individuals traveling as far west as Texas 

(Fertl et al., 2005). A species description is presented in (MMS, 2007b; BOEM, 2013) and in the 

recovery plan for this species (USFWS, 2001). 

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil 

spill. A small fuel spill in the lease area would be unlikely to affect manatees, as the lease area is 

approximately 84 miles (135 km) from the nearest shoreline (Louisiana). As explained in 

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

prior to breaking up. Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine 

debris-related impacts on manatees. Consistent with the analysis in BOEM (2012a), impacts of 

routine project-related activities on the manatee would be negligible. 

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel 

strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). 

To reduce the potential for vessel strikes, BOEM has issued NTL 2012-JOINT-G01, which 

recommends protected species identification training and that vessel operators and crews 

maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid 

striking protected species, and requires operators to report sightings of any injured or dead 

protected species. Compliance with NTL 2012-JOINT-G01 will minimize the likelihood of vessel 

strikes, and no significant impacts on manatees are expected. 

Helicopter traffic, if present, also has the potential to disturb manatees. Rathbun (1988) 

reported that manatees were disturbed more by helicopters than by fixed-wing aircraft; however, 

the helicopter was flown at relatively low altitudes of 66 to 525 ft (20 to 160 m). Helicopters 

used in support operations maintain a minimum altitude of 700 ft (213 m) while in transit 

offshore, 1,000 ft (305 m) over unpopulated areas or across coastlines, and 2,000 ft (610 m) 

over populated areas and sensitive habitats such as wildlife refuges and park properties. In 

addition, guidelines and regulations specify that helicopters maintain an altitude of 1,000 ft (305 

m) within 300 ft (91 m) of marine mammals (BOEM, 2012a,b). This mitigation measure will 

minimize the potential for disturbing manatees, and no significant impacts are expected. 

Impacts of a Large Oil Spill

The OSRA results summarized in Table 3 predict that some Louisiana and Florida shorelines 

could be contacted by a spill within 30 days. There is no critical habitat designated in these 

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areas, and the number of manatees potentially present is a small fraction of the population in 

peninsular Florida. 

In the event that manatees are exposed to oil, effects could include direct impacts from oil 

exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, 

noise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin 

irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; 

inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated 

vegetation; and stress from the activities and noise of response vessels and aircraft. 

Complications of the above may lead to dysfunction of immune and reproductive systems, 

physiological stress, declining physical condition, and death. Behavioral responses can include 

displacement of animals from prime habitat, disruption of social structure, change in prey 

availability and foraging distribution or patterns, change in reproductive behavior/productivity, 

and change in movement patterns or migration (MMC, 2011). 

In the event that a large spill reaches coastal waters where manatees are present, the level of 

vessel and aircraft activity associated with spill response could disturb manatees and potentially 

result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate 

in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these 

animals, and therefore no significant impacts are expected. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on manatees are expected. 

C.3.3 Endangered Mysticete Whales

Five endangered mysticetes (blue whale, fin whale, humpback whale, North Atlantic right whale, 

and sei whale) have been reported in the Gulf of Mexico but are considered rare or extralimital 

there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf 

of Mexico. 

Due to the rare occurrence of these whales in the Gulf of Mexico, it is unlikely that any 

endangered mysticete would come into contact with any project activities, either routine 

operations or accidents. 

Mysticetes were not included as affected species in the Biological Opinion for the Five-Year Oil 

and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico 

(NMFS, 2007). Potential impacts analyzed in MMS (2007b) and BOEM (2012a,b,d, 2013) are 

incorporated by reference. If any of these whales are present in the area, potential impacts 

would be the same as those discussed below in Section C.3.4. 

C.3.4 Non-Endangered Marine Mammals (Protected)

In addition to the seven endangered species that have been cited previously, 22 additional 

species of marine mammals may be found in the Gulf of Mexico, including 2 species of 

mysticetes, the dwarf and pygmy sperm whales, 4 species of beaked whales, and 14 species of 

dolphins (see DOCD 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 in this section, and additional information on protected marine mammals is 

presented in MMS (2007b) and BOEM (2012a,b,d, 2013). 

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Mysticete whales. Two species of non-endangered mysticetes are known to occur in the Gulf of 

Mexico: the Bryde’s whale (Balaenoptera edeni) and minke whale (Balaenoptera acutorostrata). 

The Bryde’s whale has been sighted most frequently along the 328-ft (100-m) isobath (Davis and 

Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto Canyon region 

and off western Florida, although there have been some in the west-central portion of the 

northeastern Gulf. The minke whale is considered rare in the Gulf of Mexico, with the only 

confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it 

is possible that Bryde’s whales could occur in the lease area.

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

(Kogia sima) from pygmy sperm whales (Kogia breviceps), and sightings are often grouped 

together as “Kogia spp.” Both species have a worldwide distribution in temperate to tropical 

waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and 

in deeper waters off the continental shelf (Mullin et al., 1991; Mullin, 2007; Waring et al., 2013). 

Either species could occur in the lease area. 

Beaked whales. Four species of beaked whales are known to occur in the Gulf of Mexico: 

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 beaked whale is extralimital. Due to the difficulties of at-sea 

identification, beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales 

or are grouped into an undifferentiated complex (Mesoplodon spp. and Ziphius spp.). In the 

northern Gulf of Mexico, they are broadly distributed in waters greater than 3,281 ft (1,000 m) 

over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in 

the lease area (Waring et al., 2013). 

Delphinids. Fourteen species of delphinids are known to occur in the Gulf of Mexico, including 

Atlantic spotted dolphin (Stenella frontalis), bottlenose dolphin (Tursiops truncatus), 

Clymene dolphin (Stenella clymene), false killer whale (Pseudorca crassidens), Fraser’s dolphin 

(Lagenodelphis hosei), killer whale (Orcinus orca), melon-headed whale (Peponocephala electra), 

pantropical spotted dolphin (Stenella attenuata), pygmy killer whale (Feresa attenuata), 

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

rough-toothed dolphin (Steno bredanensis), spinner dolphin (Stenella longirostris), and 

striped dolphin (Stenella coeruleoalba). The most common non-endangered cetaceans in the 

deepwater environment are the pantropical spotted dolphin, spinner dolphin, and 

Clymene dolphin. However, any of these species could occur in the lease area (Waring et al., 

2013). 

The bottlenose dolphin is a common inhabitant of the northern Gulf of Mexico, particularly within 

continental shelf waters. There are two ecotypes of bottlenose dolphins, a coastal form and an 

offshore form, which are genetically isolated from each other (Waring et al., 2013). The offshore 

form of the bottlenose dolphin may occur within the lease area. Inshore populations of coastal 

bottlenose dolphins in the northern Gulf of Mexico are separated by NMFS into 37 geographically 

distinct population units, or stocks, for management purposes (Waring et al., 2013). NMFS has 

classified the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the 

Bay, Sound, and Estuarine Stocks as strategic stocks (Waring et al., 2013). A “strategic” stock is 

defined by the MMPA as a marine mammal stock. 

for which the level of direct human-caused mortality exceeds the potential biological removal 

level; 

which, based on the best available scientific information, is declining and is likely to be listed as a 

threatened species under the ESA within the foreseeable future; or 

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which is listed as a threatened or endangered species under the ESA, or is designated as 

depleted under the MMPA. 

The strategic stock designation in this case was based primarily on the occurrence of an “Unusual 

Mortality Event” (UME) of unprecedented size and duration that has affected these stock areas. 

This UME began in February 2010 and, as of late 2013, the event was still considered to be 

ongoing (Waring et al., 2013). Carmichael et al. (2012) hypothesized that the unusual number of 

bottlenose dolphin strandings in the northern Gulf of Mexico during this time may have been 

associated with environmental perturbations, including sustained cold weather and the Macondo 

spill in 2010, as well as large volumes of cold freshwater discharge in the early months of 2011. 

IPFs potentially affecting non-endangered marine mammals include drilling rig presence, noise, 

and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill 

and a large oil spill. Effluent discharges are likely to have negligible impacts on marine mammals 

due to rapid dispersion, the small area of ocean affected, the intermittent nature of the 

discharges, and the mobility of marine mammals. Compliance with NTL 2012-BSEE-G01 will 

minimize the potential for marine debris-related impacts on marine mammals. 

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most 

odontocetes use higher frequency sounds than those produced by OCS drilling activities 

(Richardson et al., 1995). Noise associated with drilling is relatively weak in intensity, and an 

individual animal’s noise exposure would be transient. Stronger noise levels will occur during 

thruster use in dynamic positioning used by support vessels. Thruster noise impacts would be 

expected at greater distances than vessel noise alone (LGL Ecological Research Associates, Ltd., 

2006) but are dependent on variables relating to thruster type and usage. It is expected that 

marine mammals within or near the lease area would be able to detect the presence of the 

drilling rig or support vessels and avoid exposure to higher energy sounds, particularly within an 

open ocean environment. 

Some odontocetes have shown increased feeding activity around lighted platforms at night (Todd 

et al., 2009). Even temporary drilling rigs present an attraction to pelagic food sources that may 

attract cetaceans (and sea turtles). Therefore, prey congregation could pose an attraction to 

protected species that exposes them to higher levels or longer durations of noise that might 

otherwise be avoided. 

There are other OCS facilities and activities near the lease area, and the region as a whole has a 

large number of similar sources. Due to the limited scope, duration, and geographic extent of 

drilling activities, this project would represent a small temporary contribution to the overall noise 

regime, and any short-term impacts are not expected to be biologically significant to marine 

mammal populations. 

Drilling rig lighting and presence are not identified as IPFs for marine mammals in MMS (2007b) 

or BOEM (2012a,b,c, 2013). Therefore, no significant impacts are expected. 

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals, and there is also a risk of 

vessel strikes. Data concerning the frequency of vessel strikes are presented in a previous lease 

sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BOEM and BSEE have issued 

NTL 2012-JOINT-G01, which recommends protected species identification training and that 

vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop 

their vessel to avoid striking protected species, and requires operators to report sightings of any 

injured or dead protected species. Vessel operators and crews are required to attempt to 

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maintain a distance of 300 ft (91 m) or greater when whales are sighted and 150 ft (45 m) when 

small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels 

must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt 

changes in direction until the cetacean has left the area. Vessel operators are required to reduce 

vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans 

are observed near an underway vessel, when safety permits. Compliance with this NTL will 

minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine 

mammals, and therefore no significant impacts are expected. 

Aircraft traffic also has the potential to disturb marine mammals (Würsig et al., 1998). However, 

while flying offshore, helicopters maintain altitudes above 700 ft (213 m) during transit to and 

from the working area. In addition, guidelines and regulations specify that helicopters maintain 

an altitude of 1,000 ft (305 m) within 300 ft (91 m) of marine mammals (BOEM, 2012a,b,c). This 

altitude will minimize the potential for disturbing marine mammals, and no significant impacts are 

expected (BOEM, 2012a,b). 

Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in previous EISs (MMS, 2007b; 

BOEM, 2012a,b,d, 2013), and oil impacts on marine mammals in general are discussed by Geraci 

and St. Aubin (1990). For this DOCD, there are no unique site-specific issues with respect to spill 

impacts on these animals. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of Shell’s OSRP is expected to mitigate 

and reduce the potential for impacts on marine mammals. DOCD Section 9b provides detail on 

spill response measures. Given the open ocean location of the lease area, the duration of a small 

spill and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that more than 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and 

noise of response vessels and aircraft (MMC, 2011). However, due to the limited areal extent 

and short duration of water quality impacts from a small fuel spill, as well as the mobility of 

marine mammals, no significant impacts are expected. 

Impacts of a Large Oil Spill

Potential spill impacts on marine mammals are discussed in MMS (2007b), BOEM (2012a,b,d, 

2013), and in Geraci and St. Aubin (1990). For this DOCD, 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, 2011). Direct physical and physiological effects can include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated 

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vegetation, in the case of manatees); and stress from the activities and noise of response vessels 

and aircraft. Complications of the above may lead to dysfunction of immune and reproductive 

systems, physiological stress, declining physical condition, and death. Behavioral responses can 

include displacement of animals from prime habitat, disruption of social structure, change in prey 

availability and foraging distribution or patterns, change in reproductive behavior/productivity, 

and change in movement patterns or migration (MMC, 2011). 

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb marine mammals and potentially result in vessel strikes, entanglement, or other 

injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to 

reduce the potential for striking or disturbing these animals, and therefore no significant impacts 

are expected. A blowout resulting in a large oil spill is an extremely rare event, and the 

probability of such an event will be minimized by Shell’s well control and blowout prevention 

measures as detailed in DOCD Section 2j. In the unlikely event of a spill, implementation of 

Shell’s OSRP will mitigate and reduce the impacts. DOCD Section 9b provides detail on spill 

response measures. Therefore, no significant spill impacts on marine mammals are expected. 

C.3.5 Sea Turtles (Endangered/Threatened)

As listed in DOCD Section 6h, five species of endangered or threatened sea turtles may be 

found near the lease area. Endangered species are the leatherback (Dermochelys coriacea), 

Kemp's ridley (Lepidochelys kempii), and hawksbill (Eretmochelys imbricata) turtles. The DPS of 

loggerhead turtle (Caretta caretta) that occurs in the Gulf of Mexico is listed as threatened, 

although other loggerhead DPSs are endangered. In March 2013, the USFWS proposed to 

designate critical habitat for this DPS including beaches in Jackson County, Mississippi; Baldwin 

County, Alabama; and Bay, Gulf, and Franklin Counties in the Florida Panhandle, as well as 

several counties in southwest Florida and the Florida Keys (78 FR18000). The green turtle 

(Chelonia mydas) is listed as threatened, except for the Florida breeding population, which is 

listed as endangered. Species descriptions are presented in BOEM (2012a, 2013). 

Leatherbacks and loggerheads are the most likely species to be present near the lease area as 

adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and nearshore 

species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea 

turtles may be present in deepwater areas, including the lease area, where they may be 

associated with Sargassum and other flotsam. 

All five sea turtle species in the Gulf of Mexico are migratory and use different marine habitats 

according to their life stage. These habitats include high-energy beaches for nesting females and 

emerging hatchlings and pelagic convergence zones for hatchling and juvenile turtles. As adults, 

green, hawksbill, and loggerhead turtles forage primarily in shallow, benthic habitats. 

Leatherbacks are the most pelagic of the sea turtles, feeding primarily on jellyfish. 

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

Loggerhead turtles – Loggerheads nest in significant numbers along the Florida Panhandle 

(Florida Fish and Wildlife Conservation Commission, 2013a) and, to a lesser extent, from 

Texas through Alabama (NMFS and USFWS, 2008). The nearest significant nesting area of 

loggerhead turtles is found in Louisiana, on beaches within the Breton NWR; 

Green and leatherback turtles – Green and leatherback turtles infrequently nest on Florida 

Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2013b,c); 

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Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach in Tamaulipas, 

Mexico (NMFS et al., 2011). Approximately 150 Kemp’s ridley turtles nested on Texas 

beaches in 2013 (Sea Turtle Restoration Project, 2013). Kemp’s ridley turtles typically do not 

nest anywhere near the project area, although there have been occasional reports of Kemp’s 

ridleys nesting in Alabama (Share the Beach, 2013); and 

Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area. 

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel 

and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill. Effluent 

discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small 

area of ocean affected, and the intermittent nature of the discharges. Compliance with 

NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on sea turtles. 

Impacts of Drilling Rig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that 

may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include 

behavioral disruption and temporary or permanent displacement from the area near the sound 

source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures 

(Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced 

during routine operations. Helicopters and service vessels may also affect sea turtles due to 

machinery noise and visual disturbances. The most likely impacts would be short-term 

behavioral changes such as diving and evasive swimming, disruption of activities, or departure 

from the area. Due to the limited scope, duration, and geographic extent of drilling activities, 

these short-term impacts are not expected to be biologically significant to sea turtle populations. 

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 

1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they 

are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). 

NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are 

insignificant. Therefore, no significant impacts are expected. 

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles, and there is also a risk of vessel 

strikes. Data show that vessel traffic is one cause of sea turtle mortality in the Gulf of Mexico 

(Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in 

clear weather, they can be difficult to spot from a moving vessel when resting below the water 

surface, during nighttime, or during periods of inclement weather. To reduce the potential for 

vessel strikes, BOEM and BSEE have issued NTL 2012-JOINT-G01, which recommends protected 

species identification training and that vessel operators and crews maintain a vigilant watch for 

sea turtles and slow down or stop their vessel to avoid striking protected species, and requires 

operators to report sightings of any injured or dead protected species. When sea turtles are 

sighted, vessel operators and crews are required to attempt to maintain a distance of 150 ft 

(45 m) or greater whenever possible. Compliance with this NTL will minimize the likelihood of 

vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007). 

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, 

helicopters maintain altitudes above 700 ft (213 m) during transit to and from the working area. 

This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are 

expected. 

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Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in MMS (2007b), NMFS (2007), and BOEM 

(2012b,c, 2013). For this DOCD, there are no unique site-specific issues with respect to spill 

impacts on these animals. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of Shell’s OSRP is expected to mitigate 

and reduce the potential for impacts on sea turtles. DOCD Section 9b provides detail on spill 

response measures. Given the open ocean location of the lease area, the duration of a small spill 

and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that over 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and 

noise of response vessels and aircraft (MMS, 2007b; NMFS, 2010b; BOEM, 2012b,c). However, 

due to the limited areal extent and short duration of water quality impacts from a small fuel spill, 

no significant impacts would be expected. 

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches because 

the lease area is 84 miles (135 km) from the nearest shoreline (Louisiana). As explained in 

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

prior to breaking up. 

Impacts of a Large Oil Spill

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect 

impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). 

Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; 

chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g., 

from in situ burning of oil); ingestion of oil (and dispersants) directly or via contaminated food; 

and stress from the activities and noise of response vessels and aircraft. Complications of the 

above may lead to dysfunction of immune and reproductive systems, physiological stress, 

declining physical condition, and death. Behavioral responses can include displacement of 

animals from prime habitat, disruption of social structure, change in food availability and foraging 

distribution or patterns, change in reproductive behavior/productivity, and change in movement 

patterns or migration (MMS, 2007b; NMFS, 2010c). 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. DOCD Section 9b provides detail on spill response measures. 

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that 

sea turtles show no avoidance behavior when they encounter an oil slick, and any sea turtle in an 

affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at 

risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface over 

time, which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007). 

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The OSRA results summarized in Table 3 predict that some shorelines that support sea turtle 

nesting could be contacted within 30 days. The nearest nesting area of loggerhead turtles is 

found in St. Bernard Parish, Louisiana, on beaches within the Breton NWR. This area has a 

contact probability of 2% after 30 days. 

Spilled oil reaching sea turtle nesting beaches could have effects on nesting sea turtles and egg 

development (NMFS, 2007). An oiled beach could affect nest site selection or result in no nesting 

at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are 

subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil 

residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired 

movement and normal bodily functions (NMFS, 2007). 

NOAA’s Office of Response and Restoration prepared guidelines in 2007 to minimize impacts to 

nesting activities and existing nests due to beach cleanup activities (Shigenaka, 2010). Oil spill 

cleanup activities on the beach (e.g., raking, shoveling, using mechanical equipment) may 

adversely affect sea turtle nesting activity or existing beach nests. Response workers and 

vehicles may crush eggs and compact beach sand, making it difficult or impossible for hatchlings 

to emerge or for females to use for nesting (Shigenaka, 2010). Nighttime human activity can 

prevent sea turtles from coming ashore, may cause females to stop nesting and return to the 

ocean, disorient or impede emerging hatchlings, and crush hatchlings attempting to reach the 

ocean. 

Impacts to sea turtles from a large oil spill and associated cleanup activities would be dependent 

upon spill extent, duration, and season (relative to turtle nesting season); the amount of oil 

reaching the shore; the importance of specific beaches to sea turtle nesting; and the level of 

cleanup vessel and beach crew activity required. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on sea turtles are expected. 

C.3.6 Piping Plover (Threatened)

The Piping Plover (Charadrius melodus) is a migratory shorebird that overwinters along the 

southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of 

hunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical 

overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, 

Alabama, and Florida (Figure 1). Piping Plovers inhabit coastal sandy beaches and mudflats, 

feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to 

foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in 

recent lease sale EISs (MMS, 2007b; BOEM, 2013). 

A large oil spill is the only IPF potentially affecting Piping Plovers. There are no IPFs associated 

with routine project activities that could affect these birds. A small fuel spill in the lease area 

would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to 

make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2).

Impacts of a Large Oil Spill

The lease area is 86 miles (138 km) from the nearest shoreline designated as critical habitat for 

Piping Plovers. The OSRA results summarized in Table 3 predict that Louisiana and Florida 

shorelines designated as critical habitat for the wintering Piping Plover could be contacted by a 

spill within 30 days. Plaquemines Parish, Louisiana, which has the highest probability of contact 

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for the 10-day and 30-day intervals (5% and 11%, respectively), includes Piping Plover critical 

habitat. 

Plovers could become externally oiled while foraging on oiled shores or be exposed internally 

through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and 

feed along tidally exposed banks and shorelines, following the tide out and foraging at the 

water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills 

occur during winter months when plovers are most common along the coastal Gulf or if spills 

contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other 

activities associated with spill cleanup. Shell has extensive resources available to protect and 

rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 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 (National Wildlife Federation, 2012). 

One population winters along the Texas coast at Aransas NWR and summers at Wood Buffalo 

National Park in Canada. This population represents the majority of the world’s population of 

free-ranging Whooping Cranes and reached a record population of 278 at Aransas/Wood Buffalo 

National Park in August 2011 (Whooping Crane Eastern Partnership, 2012). A non-migrating 

population has been reintroduced in central Florida, and another reintroduced population 

summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes 

breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and 

estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields 

(USFWS, 2007). Approximately 22,240 ac (9,000 ha) of salt flats in Aransas NWR and adjacent 

islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is 

designated as critical habitat for the species (Figure 1). A species description is presented in 

MMS (2007b) and BOEM (2012b,c, 2013). 

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Figure 1. Location of selected environmental features in relation to the lease area. 

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A large oil spill is the only IPF that could potentially affect Whooping Cranes due to the distance 

from Aransas NWR. 

Impacts of a Large Oil Spill

A large oil spill has a low probability of affecting Whooping Cranes because the lease area is 

approximately 518 miles (834 km) from its critical habitat (Aransas NWR, Texas) and the 

likelihood of contact is extremely low (BOEM, 2012b). 

In the event of oil exposure, Whooping Cranes could become externally oiled while foraging in 

oiled areas or internally exposed to oil through ingestion of contaminated shellfish, frogs, and 

fishes. It is possible that some death of Whooping Cranes could occur. Shell has extensive 

resources available to protect and rehabilitate wildlife in the event of a spill reaching the 

shoreline, as detailed in the OSRP. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on Whooping Cranes are expected. 

C.3.8 Gulf Sturgeon (Threatened)

The Gulf sturgeon (Acipenser oxyrinchus desotoi) is a threatened fish species that inhabits major 

rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 

1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal 

rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, 

Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner 

shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been 

depleted or even extirpated throughout this range by fishing, shoreline development, dam 

construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These 

declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best 

known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak 

and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl 

River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake 

Borgne, Louisiana (St. Bernard Parish), to Suwannee Sound, Florida (Levy County) (NMFS, 

2010d) (Figure 1). A species description is presented in a recent lease sale EIS (MMS, 2007b) 

and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 

1995). 

A large oil spill is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated 

with routine project activities that could affect this species. A small fuel spill in the lease area 

would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to 

make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2). 

Impacts of a Large Oil Spill

Potential spill impacts on Gulf sturgeon are discussed in MMS (2007b), NMFS (2007), and BOEM 

(2012b,c, 2013). For this DOCD, there are no unique site-specific issues with respect to this 

species. 

The lease area is approximately 130 miles (209 km) from the nearest Gulf sturgeon critical 

habitat. OSRA modeling (Table 3) predicts that a spill in the lease area has a 2% probability of 

contacting coastal areas inhabited by Gulf sturgeon within 30 days. 

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In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, 

ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. 

Based on the life history of this species, sub-adult and adult Gulf sturgeon would be most 

vulnerable to a marine oil spill, and would be vulnerable 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 is an extremely rare event, and the probability of such an 

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

DOCD 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. 

DOCD Section 9b provides 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, Choctawhatchee, 

Perdido Key, and St. Andrew beach mouse. Critical habitat has been designated for all four 

subspecies; Figure 1 shows the critical habitat combined for all four subspecies. Species 

descriptions are provided in recent lease sale EISs (MMS, 2007b; BOEM, 2013). 

A large oil spill is the only IPF potentially affecting subspecies of beach mouse. There are no 

IPFs associated with routine project activities that could affect these animals due to the distance 

from shore and the lack of onshore support activities near their habitat. 

Impacts of a Large Oil Spill

Potential spill impacts on beach mice are discussed in recent EISs (MMS, 2007b; BOEM, 2012b,c, 

2013). For this DOCD, there are no unique site-specific issues with respect to these species. 

The lease area is approximately 130 miles (209 km) from the nearest beach mouse critical 

habitat. OSRA modeling (Table 3) predicts that a spill in the lease area has a 1% probability of 

contacting beach mouse critical habitat within 30 days. In the event of oil contacting these 

beaches, beach mice could experience several types of direct and indirect impacts. Contact with 

spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of 

sweat glands, ear tissues, and throat tissues; disruption of sight and hearing; asphyxiation from 

inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts 

could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts 

could also occur from vehicular traffic and other activities associated with spill cleanup. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on beach mice are expected. 

C.4 Coastal and Marine Birds

C.4.1 Marine and Pelagic Birds

A variety of seabirds may occur in the pelagic environment of the project areas (Clapp et al., 

1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore 

over the open ocean, except during breeding season when they nest along the coast. In 

addition, other birds such as waterfowl, marsh birds, and shorebirds may occasionally be present 

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over open ocean areas. No endangered or threatened bird species are likely to occur at the 

project area due to the distance from shore. For a discussion of shorebirds and coastal nesting 

birds, see Section C.4.2. 

Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. 

Hess and Ribic (2000) reported that terns, storm petrels, shearwaters, and jaegers were the 

most frequently sighted seabirds in the deepwater area. From these surveys, four ecological 

categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants 

(shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Sooty Tern, 

Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); 

and permanent resident species (Laughing Gull, Royal Tern, Bridled Tern) (Hess and Ribic, 2000). 

Common seabird species include Wilson’s Storm Petrel (Oceanites oceanicus), Magnificent 

Frigatebird (Fregata magnificens), Northern Gannet (Morus bassanus), Masked Booby 

(Sula dactylatra), Brown Booby (Sula leucogaster), Cory’s Shearwater (Calonectris diomedea), 

Greater Shearwater (Puffinus gravis), and Audubon Shearwater (Puffinus lherminieri). Seabirds 

are distributed Gulf-wide and are not specifically associated with the lease area. 

Relationships with hydrographic features were found for several seabird species, possibly due to 

effects of hydrography on nutrient levels and productivity of surface waters where birds forage. 

GulfCet II did not estimate bird densities; however, Powers (1987) indicates that seabird 

densities over the open ocean typically are <10 birds/km2. 

Trans-Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be 

present in the lease area. Migrant birds may use offshore structures and platforms for resting, 

feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be 

attracted to offshore structures because of the lights and the fish populations that aggregate 

around these structures. 

IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; 

support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil 

spill. Effluent discharges from drilling rigs, which are permitted under the NPDES general permit 

are likely to have negligible impacts on the birds due to rapid dispersion, the small area of ocean 

affected, the intermittent nature of the discharges, and the mobility of these animals. 

Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related 

impacts on birds. 

Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent platforms may be exposed to contaminants including air pollutants and 

routine discharges, but significant impacts are unlikely due to rapid dispersion of effluents and air 

pollutants. Birds migrating over water have been known to strike offshore structures, resulting in 

death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and 

other land-based structures has been reviewed extensively, and the mechanisms involved in 

platform collisions appear to be similar. In some cases, migrants simply do not see a part of the 

platform until it is too late to avoid it. In other cases, navigation may be disrupted by noise 

(Russell, 2005). However, offshore structures are suitable stopover habitats for most trans-Gulf 

migrant species, and most of the migrants that stop over on platforms probably benefit from 

their stay, particularly in spring (Russell, 2005). 

Overall, potential negative impacts to birds for this project from drilling rig lighting, potential 

collisions, or other adverse effects are highly localized, relatively short-term and temporary in 

nature, and may be expected to affect only individual birds during migration periods. Therefore, 

these potential impacts are not expected to affect birds at the population or species level and are 

not significant (BOEM, 2012b). 

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Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore 

waters. It is likely that individual birds would experience, at most, only short-term behavioral 

disruption, and the impact would not be significant. 

Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in MMS (2007b) and BOEM (2012b,c, 2013). 

For this DOCD, there are no unique site-specific issues with respect to spill impacts on these 

animals. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts on marine and pelagic birds. DOCD Section 

9b provides detail on spill response measures. Given the open ocean location of the lease area, 

the duration of a small spill and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that over 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

Birds exposed to oil on the sea surface could experience direct physical and physiological effects 

including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of 

toxic fumes. Due to the limited areal extent and short duration of water quality impacts from a 

small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in 

prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small 

area affected, and the brief duration of the surface slick, no significant impacts on marine and 

pelagic birds would be expected. 

Impacts of a Large Oil Spill

Potential spill impacts on marine and pelagic birds are discussed in MMS (2007b) and BOEM 

(2012b,c, 2013). For this DOCD, there are no unique site-specific issues with respect to spill 

impacts on these animals. 

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) 

reported that terns, storm petrels, shearwaters, and jaegers were the most frequently sighted 

seabirds in the deepwater Gulf of Mexico (>656 ft [>200 m]). Powers (1987) indicates that 

seabird densities over the open ocean typically are <10 birds/km2. The number of pelagic birds 

that could be affected in open, offshore waters would depend on the extent and persistence of 

the oil slick. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on marine and pelagic birds are expected. 

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C.4.2 Shorebirds and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) are discussed in 

Section C.3. Various species of non-endangered birds are also found along the northern 

Gulf Coast, including diving birds, shorebirds, marsh birds, wading birds, and waterfowl. 

Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. 

Species that breed on beaches, flats, dunes, bars, barrier islands, and similar habitats include the 

Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull-Billed Tern, Laughing Gull, 

Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in MMS (2007b) 

and BOEM (2012b, 2013). 

The Brown Pelican (Pelecanus occidentalis) was delisted from federal endangered status in 2009 

(USFWS, 2010c). However, this species remains on the Louisiana list of Endangered Species 

(State of Louisiana Department of Wildlife and Fisheries, 2013), is listed as a species of greatest 

conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and 

Parks, 2005) and as a species of special concern by the State of Florida (Florida Fish and Wildlife 

Conservation Commission, 2013d). Brown Pelicans inhabit coastal habitats and forage within 

both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, 

including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur over deep offshore 

waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the 

southeastern population of Brown Pelicans lives in the northern Gulf Coast, generally nesting on 

protected islands (USFWS, 2010b). 

IPFs potentially affecting shorebirds and coastal nesting birds include support vessel and 

helicopter traffic and a large oil spill. As explained in Section A.9.2, a small fuel spill would not 

be expected to make landfall or reach coastal waters prior to breaking up. Compliance with 

NTL 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on shorebirds. 

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas near Port Fourchon and Boothville, 

Louisiana, where shorebirds and coastal nesting birds may be found. These activities could 

periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands 

that may support feeding, resting, or breeding birds). 

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary among 

species and individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to 

flushing birds away from vessel pathways; known distances are from 65 to 160 ft (20 to 49 m) 

for personal watercrafts and 75 to 190 ft (23 to 58 m) for outboard-powered boats (Rodgers and 

Schwikert, 2002). Flushing distances may be similar or less for the support vessels to be used for 

Shell’s project, and some species such as gulls are attracted to boats. Support vessels will not 

approach nesting or breeding areas on the shoreline, so nesting birds, eggs, and chicks will not 

be disturbed. Vessel operators will use designated navigation channels and comply with posted 

speed and wake restrictions while transiting sensitive inland waterways. Due to the limited 

scope, duration, and geographic extent of drilling activities, any short-term impacts are not 

expected to be biologically significant to coastal bird populations. 

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly 

dependent on the type of aircraft, bird species, activities that animals were previously engaged 

in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause 

the most intense responses over other human disturbances for some species (Bélanger and 

Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91-36D 

recommends that pilots maintain a minimum altitude of 2,000 ft (610 m) when flying over 

noise-sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. 

This is greater than the distance (slant range) at which aircraft overflights have been reported to 

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cause behavioral effects on most species of birds studied (Efroymson et al., 2000). With these 

guidelines in effect, it is likely that individual birds would experience, at most, only short-term 

behavioral disruption. 

Impacts of Large Oil Spill

The OSRA results summarized in Table 3 predict that shorelines of Louisiana and Florida that 

include habitat for shorebirds and coastal nesting birds could be affected within 30 days. 

Studies being performed after the Macondo spill provide additional information regarding impacts 

on species of coastal birds and shorebirds that may be affected in the event that a large oil spill 

reached coastal habitats. Although the Macondo spill had direct and indirect impacts to coastal 

and marine birds, it is premature to conclude impacts over a long period (BOEM, 2012b). 

Impacts to birds from the Macondo spill are being studied as part of the Natural Resource 

Damage Assessment, but results have not yet been released. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on shorebirds and coastal nesting birds are expected. 

C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater 

environment of the northern Gulf of Mexico. The biological oceanography of the region is 

dominated by the influence of the Loop Current, the surface waters of which are among the most 

oligotrophic of the world’s oceans. Superimposed on this low-productivity condition are 

productive “hot spots” associated with entrainment of nutrient-rich Mississippi River water and 

mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an 

important role in determining biogeographic patterns and controlling primary productivity in the 

northern Gulf of Mexico (Biggs and Ressler, 2000). 

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and 

larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae 

become part of the planktonic community for various lengths of time (10 to 100 days, depending 

on the species) (MMS, 2007b). A study by Ross et al. (2012) on midwater fauna to characterize 

vertical distribution of mesopelagic fishes in selected deepwater areas in the Gulf of Mexico 

substantiated high species richness, but general domination by relatively few families and 

species. 

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, 

noise, and lights; effluent discharges; water intakes; and two types of accidents – a small fuel 

spill and a large oil spill. 

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish 

aggregating device (FAD). In oceanic waters, the FAD effect would be most pronounced for 

epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to 

fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994). The 

FAD effect could possibly enhance the feeding of epipelagic predators by attracting and 

concentrating smaller fish species. Because the drilling rig is a single, temporary structure, 

impacts on fish populations, whether beneficial or adverse, are considered minor. 

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Impacts of Effluent Discharges

Discharges of treated SBM cuttings will produce temporary, localized increases in suspended 

solids in the water column around the drilling rig. In general, turbid water can be expected to 

extend between a few hundred meters and several kilometers down current from the discharge 

point (NRC, 1983; Neff, 1987). NPDES permit limitations and requirements are expected to be 

met.

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the 

immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, 

organic matter, and chlorine, but will be diluted rapidly to undetectable levels within tens to 

hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are 

anticipated. 

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of 

these discharges. Deck drainage from contaminated areas will be passed through an oil and 

water separator prior to release, and discharges will be monitored for visible sheen. The 

discharges may have slightly elevated levels of hydrocarbons but will be diluted rapidly to 

undetectable levels within tens to hundreds of meters from the source. Minimal impacts on 

water quality, plankton, and nekton are anticipated. 

Other discharges in accordance with the NPDES permit, such as desalination unit brine and 

uncontaminated cooling water, fire water, and ballast water, are expected to be diluted rapidly 

and have little or no impact on water column biota. 

Impacts of Water Intakes

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

including firewater and once-through non-contact cooling of machinery on the drilling rig 

(DOCD Table 7a). Section 316(b) of the Clean Water Act requires NPDES permits to ensure 

that the location, design, construction, and capacity of cooling water intake structures reflect the 

best technology available to minimize adverse environmental impact from impingement and 

entrainment of aquatic organisms. The current general NPDES Permit No. GMG290000 specifies 

requirements for new facilities for which construction was commenced after July 17, 2006, with a 

cooling water intake structure having a design intake capacity of greater than 2 million gallons of 

water per day, of which at least 25% is used for cooling purposes. 

The wells will be drilled using either the using the either a DP drillship, DP semisubmersible rig , 

or an anchored semisubmersible rig. If the drilling vessel selected for this project meets the 

described applicability for new facilities, the vessel’s water intakes are expected to be in 

compliance with the design, monitoring, and recordkeeping requirements of the NPDES permit. 

Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resources are discussed in MMS (2007b) and 

BOEM (2012a,b,d, 2013). For this DOCD, there are no unique site-specific issues with respect to 

spill impacts. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts on pelagic communities, including 

ichthyoplankton. DOCD Section 9b provides detail on spill response measures. Given the open 

ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur 

would be very brief. 

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A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that over 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

A small fuel spill could have localized impacts on phytoplankton, zooplankton, ichthyoplankton, 

and nekton. Due to the limited areal extent and short duration of water quality impacts, a small 

fuel spill would be unlikely to produce detectable impacts on pelagic communities. 

Impacts of a Large Oil Spill

Potential spill impacts on pelagic communities and ichthyoplankton are discussed in 

BOEM (2012a,b,d, 2013). For this DOCD, there are no unique site-specific issues. 

A large oil spill could affect water column biota including phytoplankton, zooplankton, 

ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more 

likely to affect these communities. While adult and juvenile fishes may actively avoid a large 

spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes in 

the upper layers of the water column are especially vulnerable to oiling; certain toxic fractions of 

spilled oil may be lethal to these life stages. Impacts would be potentially greater if local scale 

currents retained planktonic larval assemblages (and the floating oil slick) within the same water 

mass. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on pelagic communities and ichthyoplankton are expected. 

C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for 

spawning, breeding, feeding, and growth to maturity. Under the Magnuson-Stevens Fishery 

Conservation and Management Act, as amended, federal agencies are required to consult 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 (GMFMC) has prepared Fishery Management 

Plans for corals and coral reefs, shrimps, spiny lobster, reef fishes, coastal migratory pelagic 

fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic 

Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). The EFH for most 

of these GMFMC-managed species is on the continental shelf in waters shallower than 600 ft 

(183 m). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, 

and shrimps. EFH for corals and coral reefs includes some shelf-edge topographic features on 

the Texas-Louisiana OCS, the nearest of which is located 58 miles (93 km) north-northwest of 

the lease area. 

EFH has been identified in the deepwater Gulf of Mexico for highly migratory pelagic fishes, 

which occur as transients in the lease area. Species in this group, including tunas, swordfishes, 

billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the 

lease area include the following (NMFS, 2009): 

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Atlantic bluefin tuna (spawn, eggs, 

larvae) 

Skipjack tuna (spawn, adults) 

Yellowfin tuna (spawn, juveniles, adults) 

Swordfish (larvae, juveniles) 

Blue marlin (juveniles, adults) 

White marlin (juveniles) 

Silky shark (all) 

Longfin mako shark (all) 

Oceanic whitetip shark (all) 

Longbill spearfish (juveniles, adults) 

Bigeye thresher shark (all) 

Research indicates the central and western Gulf of Mexico may be important spawning habitat for 

Atlantic bluefin tuna (Thunnus thynnus), and NMFS (2009) has designated a Habitat Area of 

Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of 

Mexico, including the lease area (Figure 1). The areal extent of the HAPC is approximately 

115,830 mi2 (300,000 km2). The prevailing assumption is that Atlantic bluefin tuna follow an 

annual cycle of foraging in June through March off the eastern United 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 Mexico by the GMFMC (2005). These include the 

Florida Middle Grounds, Madison-Swanson Marine Reserve, Tortugas North and South Ecological 

Reserves, Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico 

(Figure 1). The nearest of these is Jakkula Bank, located 222 miles (357 km) west of the lease 

area. 

Routine IPFs potentially affecting EFH and fisheries resources include drilling rig presence, noise, 

and lights; effluent discharges; and water intakes. In addition, two types of accidents – a small 

fuel spill and a large oil spill may potentially affect EFH and fisheries resources. 

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as an FAD. In 

oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, 

dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface 

structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994). The FAD effect would 

possibly enhance feeding of epipelagic predators by attracting and concentrating smaller fish 

species. Any impacts on EFH for highly migratory pelagic fishes are considered minor. 

Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling mud 

and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous discharges 

such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water. 

Impacts on water quality have been discussed previously. No significant impacts on EFH for 

highly migratory pelagic fishes are expected from these discharges. 

Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, 

including fish eggs and larvae (ichthyoplankton). Due to the limited scope, duration, and 

geographic extent of drilling activities, any short-term impacts on EFH for highly migratory 

pelagic fishes are not expected to be biologically significant. 

Impacts of a Small Fuel Spill

Potential spill impacts on EFH are discussed in MMS (2007b) and BOEM (2012a,b,d, 2013). For 

this DOCD, there are no unique site-specific issues with respect to spill impacts. 

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

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will mitigate and reduce the potential for impacts on EFH. DOCD Section 9b provides detail on 

spill response measures. Given the open ocean location of the lease area, the duration of a small 

spill and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the 

time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of 

a small fuel spill and indicates that more than 90% would evaporate or disperse naturally within 

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac (0.5 to 

5 ha), depending on sea state and weather conditions. 

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, 

including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the 

lease area. A spill would also produce short-term impact on water quality in the HAPC for 

spawning Atlantic bluefin tuna, which covers much of the deepwater Gulf of Mexico. The 

affected area would represent a negligible portion of the HAPC. 

A small fuel spill would not affect EFH for corals and coral reefs; the nearest coral EFH is 

Sackett Bank, located 58 miles (93 km) north-northwest of the lease area. A small fuel spill 

would float and dissipate on the sea surface and would not contact these features.

Impacts of a Large Oil Spill

Potential spill impacts on EFH are discussed in MMS (2007b) and BOEM (2012a,b,d, 2013). For 

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

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the 

water surface and potentially the subsurface as well. Given the extent of EFH designations in the 

Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable. 

A large spill could affect the EFH for many managed species including shrimps, spiny lobster, 

corals and coral reefs, reef fishes, coastal migratory pelagic fishes, red drum, and highly 

migratory pelagic fishes. It would result in adverse impacts on water quality and water column 

biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. In coastal waters, 

sediments could be contaminated and result in persistent degradation of the seafloor habitat for 

managed demersal fish and invertebrates. 

The lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill 

could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water 

column, with the potential for lethal or sublethal impacts on spawning tuna and their offspring. 

Potential impacts would depend in part on the timing of a spill, as this species migrates to the 

Gulf of Mexico to spawn in April, May, and June (NMFS, 2009). 

The nearest feature designated as EFH for corals is located 58 miles (93 km) north-northwest of 

the lease area. An accidental spill would be unlikely to reach or affect this feature. Near-bottom 

currents in the region are expected to flow along the isobaths (Nowlin et al., 2001) and typically 

would not carry a plume up onto the continental shelf edge. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on EFH are expected. 

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C.6 Archaeological Resources

C.6.1 Shipwreck Sites

MC 657 is on the list of archaeological survey blocks determined to have a high potential for 

containing archaeological properties (BOEM, 2012d). The archaeological surveys conducted by 

Marmaduke & Associates, LLS (2005) and C&C Technologies, Inc. (2006) detected 

37 unidentified sonar contacts, including 35 isolated targets, one debris zone, and one shipwreck. 

Thirty-one of the isolated targets were determined to be modern debris or geologic features and 

were not recommended for archaeological investigation. The remaining four isolated targets 

were determined to potentially be outlying shipwreck debris and are located within the existing 

avoidance zone for the wreck and no additional avoidance zones beyond the 2,000 ft (610 m) 

avoidance zone were recommended. The debris field was determined to likely be modern or 

geologic, and is not considered to have historic or archaeological significance (C&C Technologies, 

Inc., 2006). 

The shipwreck was originally located during a 1986 deep-tow survey, and is located 

approximately 8,900 ft (2,713 m) to the south of the proposed wellsites. Acoustic data were 

analyzed and results suggest that the MC 657 shipwreck is probably a historic wooden sailing 

vessel which is embedded up to 6 ft (2 m) in the seafloor. Comparison of side-scan sonar 

imagery of the MC 657 wreck and the known copper-clad Petronius wreck in the Viosca Knoll 

area suggest that the MC 657 wreck may be copper clad. 

The 2,000 ft (610 m) avoidance zone will be maintained and Shell will avoid all contact with the 

shipwreck and the potential outlying shipwreck debris. It is possible that other shipwrecks are 

present in the area or that debris from the identified wreck is spread beyond the 2,000 ft (610 m) 

avoidance zone. Shell will cooperate with guidance from BOEM regarding the MC 657 wreck or 

other identified shipwrecks or shipwreck debris in the project area. 

A small fuel spill would not affect the MC 657 wreck or shipwrecks in adjoining blocks because 

the oil would float and dissipate on the sea surface. 

Impacts of a Large Oil Spill

The historic shipwreck in MC 657 could potentially be impacted by a large oil spill in the lease 

area. Previous analyses (MMS, 2007a) concluded that oil spills would be unlikely to affect 

archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts 

of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. 

However, during the Macondo spill, subsurface plumes were reported at a water depth of about 

3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsite and persisting for more 

than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of 

dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of 

subsurface plumes are not well known, a subsurface plume could contact shipwreck sites beyond 

the 984-ft (300-m) radius estimated by MMS (2007a) and BOEM (2012a), depending on its 

extent, trajectory, and persistence. The identified shipwreck in MC 657 is located approximately 

8,900 ft (2,713 m) south of the proposed wellsites and therefore would be unlikely to be 

contacted by the physical impacts of a blowout, but could be contacted by a subsurface plume 

depending on its extent and trajectory. 

BOEM (2012b) reexamined the analyses for archaeological resources presented in MMS (2007a) 

based on additional information available and in consideration of the Macondo oil spill. 

Substantial new information that alters the initial impact conclusion for archaeological resources 

has come to light as a result of BOEM-sponsored studies and industry surveys. Specifically, 

evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to 

have occurred because of an incomplete knowledge of seafloor conditions in lease areas >200 m 

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(>656 ft) deep that have been exempted from high-resolution surveys. Since significant historic 

shipwrecks recently had been discovered outside the previously designated high probability areas 

(some of which show evidence of impacts from permitted activities prior to their discovery), 

BOEM now requires surveys of areas potentially affected by exploration and development 

projects. 

A spill entering shallow coastal waters could conceivably contaminate an undiscovered or known 

historic shipwreck site. The OSRA modeling summarized in Table 3 predicts that Louisiana and 

Florida shorelines could be contacted by a spill within 30 days. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

MMS (2007b) assumed that an oil spill contacting a coastal historic site, such as a fort or a 

lighthouse, would cause only temporary, reversible visual impacts from oil contact and 

contamination of the site and its environment. However, more recent studies suggest that the 

unavoidable direct and indirect impacts could be longer term and not easily reversible (BOEM, 

2012b,c). 

C.6.2 Prehistoric Archaeological Sites

With a water depth of approximately 7,553 ft (2,302 m), the wellsites are well beyond the 197-ft 

(60-m) depth contour used by BOEM as the seaward extent for prehistoric archaeological site 

potential in the Gulf of Mexico. Because prehistoric archaeological sites would not occur in the 

lease area, the only relevant IPF is a large oil spill that would reach coastal waters within the 

197-ft (60-m) depth contour. 

Impacts of a Large Oil Spill

Because prehistoric archaeological sites would not occur in the lease area, they would not be 

affected by the physical effects of a subsea blowout. BOEM (2012a) estimates that a severe 

subsurface blowout could resuspend and disperse sediments within a 984-ft (300-m) radius. 

Along the northern Gulf Coast, prehistoric sites occur frequently along the barrier islands and 

mainland coast and along the margins of bays and bayous (MMS, 2007b). The OSRA modeling 

summarized in Table 3 predicts that Louisiana and Florida shorelines could be contacted by a 

spill within 30 days. A spill reaching a prehistoric site along these shorelines could coat fragile 

artifacts or site features and compromise the potential for radiocarbon dating organic materials in 

a site (although other dating methods are available and it is possible to decontaminate an oiled 

sample for radiocarbon dating). If appropriate measures are not in place, coastal prehistoric 

sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and 

disturbing the provenance of artifacts and site features). 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on archaeological resources are expected. 

C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northern Gulf of Mexico that may be affected by oil and gas activities are 

described in EISs (MMS, 2007b; BOEM, 2012a,b,d, 2013) and in a literature review by Collard 

and Way (1997). Sensitive coastal habitats are also tabulated in the OSRP. Coastal habitats 

inshore of the project area include barrier beaches and dunes, wetlands, and submerged 

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seagrass beds. Most of the northern Gulf is fringed by barrier beaches, with wetlands and 

submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries. 

Due to the distance from shore, there are no IPFs associated with routine activities that are likely 

to affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, 

or any other managed or protected coastal area. The support bases at Port Fourchon and 

Boothville are not located in a wildlife refuge or a wilderness area. Potential impacts of support 

vessel traffic are briefly addressed below. 

A small fuel spill in the lease area would be unlikely to affect coastal habitats because it would 

not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in 

Section A.9.2).

Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including the crew boat and supply boats, may 

have a minor incremental impact on coastal habitats. Over time with a large number of vessel 

trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support operations, 

including the crew boat and supply boats as detailed in DOCD Section 14, may have a minor 

incremental impact on coastal habitats or protected areas. Impacts will be minimized by 

following the speed and wake restrictions in harbors and channels. 

Impacts of a Large Oil Spill

Potential spill impacts on coastal habitats are discussed in MMS (2007b) and BOEM (2012a,b,d, 

2013). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, 

and submerged seagrass beds. For this DOCD, there are no unique site-specific issues with 

respect to coastal habitats. 

The OSRA results summarized in Table 3 predict that shorelines of Louisiana and Florida could 

be affected within 30 days. Plaquemines Parish, Louisiana has the highest probability of contact 

for the 10-day and 30-day intervals (5% and 11%, respectively). One other Louisiana parish 

(Lafourche) may be contacted within 10 days. After 30 days, seven Louisiana parishes and two 

counties on the Florida Panhandle may be contacted, ranging from Cameron Parish, Louisiana to 

Bay County, Florida. 

The shorelines within the geographic range predicted by the OSRA modeling include extensive 

barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered areas behind 

the barrier islands and in estuaries. NWRs and other protected areas along the coast are 

discussed in the lease sale EIS (MMS, 2007b) and Shell’s OSRP. Coastal wildlife refuges, 

wilderness areas, and state and national parks within the geographic range of the potential 

shoreline contacts after 30 days include the following: 

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Atchafalaya Delta Wildlife Management 

Area (WMA) 

Bayou Sauvage NWR 

Biloxi WMA 

Breton NWR 

Cameron Prairie NWR 

Choctawhatchee Bay Surface Water 

Improvement and Management 

(SWIM) Area 

Deer Lake State Park 

Delta NWR 

Grand Isle State Park 

Grayton Beach State Park Outstanding 

Florida Water 

Henderson State Park 

Isles Dernieres Barrier Islands Refuge 

Jean Lafitte National Historical Park and 

Preserve 

Lacassine NWR 

Lafitte Woods Natural Area 

Little Pecan Island Natural Area 

Lower Neches WMA 

Mandalay NWR 

Pass Au Loutre WMA 

Paul J. Rainey WMA 

Peveto Woods Natural Area 

Point Au Chien WMA 

Point Washington Outstanding Florida 

Water 

Rockefeller WMA 

Sabine NWR 

Salvador WMA 

St. Andrew Bay Watershed SWIM Area 

St. Andrews State Park 

St. Andrews State Park Aquatic 

Preserve 

St. Bernard State Park 

Wisner WMA 

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The OSRA results in Table 3 include only shoreline segments with contact probabilities greater 

than 0.5% within 30 days; other coastal areas could be affected at lower contact probabilities 

within 30 days, or from a spill persisting for more than 30 days. Additional NWRs and managed 

wildlife areas occur along the Gulf Coast. These areas include habitats such as barrier beach and 

dune systems, wetlands, and submerged seagrass beds that support diverse wildlife, including 

endangered or threatened species. 

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil 

characteristics, the geographic location of the landfall, and the weather and oceanographic 

conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid 

weathered oil, an oil-and-water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on 

beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will 

thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that 

incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths 

under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing 

may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches 

may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at 

varying depths and may persist for several years as it slowly biodegrades and volatilizes. 

Coastal wetlands are highly sensitive to oiling and can be significantly impacted because of the 

inherent toxicity of hydrocarbon and non-hydrocarbon components of the spilled substances 

(Mendelssohn et al., 2012). MMS (2007b) predicted that for every 50 bbl of oil contacting 

wetlands, approximately 6.7 ac (2.7 ha) of wetland vegetation will experience dieback. Thirty 

percent of the damaged wetlands are assumed to recover within 4 years, and 85% within 

10 years. Approximately 15% of the contacted wetlands are expected to be converted 

permanently to open-water habitat. The critical concentration of oil is that concentration above 

which impacts to wetlands will be long-term and recovery will take longer than two growing 

seasons, and which causes plant mortality and some permanent wetland loss. Critical 

concentrations of various oils are expected to vary broadly for wetland types and wetland plant 

species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in 

the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, 

cleanup activities in marshes may accelerate rates of erosion and retard recovery rates (MMS, 

2007b). 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on coastal habitats are expected. 

C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in 

MMS (2007b) based on additional information and in consideration of the Macondo spill. No new 

information was found that would alter the potential impacts on commercial fishing (BOEMRE, 

2011; BOEM, 2012b,c, 2013). The main commercial fishing activity in deep waters of the 

northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes 

(Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the 

project area, primarily during spring and summer. 

It is unlikely that any commercial fishing activity other than longlining occurs at or near the 

project area. Benthic species targeted by commercial fishers occur on the upper continental 

slope, well inshore of the project area. Royal red shrimp (Pleoticus robustus) are caught by 

trawlers in water depths of approximately 820 to 1,804 ft (250 to 550 m). Tilefishes (primarily 

Lophalotilus chamaeleonticeps) are caught by bottom longlining in water depths from 

approximately 540 to 1,476 ft (165 to 450 m) (Continental Shelf Associates, Inc., 2002). The 

proposed project is in approximately 3,853 ft (1,174 m) of water. No conflict with commercial 

fishing activity is expected to occur. 

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Most recreational fishing activity in the region occurs in water depths less than 656 ft (200 m) 

(Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to 

recreational fishers would be petroleum platforms in offshore waters of Texas and Louisiana. 

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and 

lights). Two types of potential accidents are also addressed below – a small fuel spill and a large 

oil spill. 

Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For 

example, in January 1999 a portion of a pelagic longline snagged on the acoustic Doppler current 

profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The 

line was removed without incident. Generally, longline fishers use radar and are aware of 

offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic 

longlining is expected. 

No adverse impacts on fishing activities are anticipated. Other factors such as effluent 

discharges are likely to have negligible impacts on commercial or recreational fisheries due to 

rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. 

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts. DOCD Section 9b provides detail on spill 

response measures. Given the open ocean location of the lease area, the duration of a small spill 

and opportunity for impacts to occur would be very brief. 

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small 

fuel spill. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 ac 

(0.5 to 5 ha), depending on sea state and weather conditions. Fishing activities could be 

interrupted due to the activities of response vessels operating in the lease area. A small fuel spill 

would not affect coastal water quality because the spill would not be expected to make landfall or 

reach coastal waters prior to breaking up (see Section A.9.2).

Impacts of a Large Oil Spill

Potential spill impacts on fishing activities are discussed in MMS (2007b) and BOEM (2012b,c, 

2013). For this DOCD, there are no unique site-specific issues with respect to this activity. 

Pelagic longlining activities in the lease area and other fishing activities in the northern 

Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result 

in fishery closures, depending on the duration of the spill, the oceanographic and meteorological 

conditions at the time, and the effectiveness of spill response measures. A blowout resulting in a 

large oil spill is an extremely rare event, and the probability of such an event will be minimized by 

Shell’s well control and blowout prevention measures as detailed in DOCD Section 2j. In the 

unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. 

DOCD Section 9b provides detail on spill response measures. Therefore, no significant spill 

impacts on fishing activities are expected. 

C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health 

and safety. Impacts of a small fuel spill and a large oil spill are addressed below. 

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts. DOCD Section 9b provides detail on spill 

response measures. 

A small fuel spill would not have impacts on public health and safety because it would likely 

affect only a small area of the open ocean 84 miles (135 km) from the nearest shoreline and 

nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response 

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crews would be equipped with appropriate safety equipment to avoid injury and health effects. 

A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking 

up (see Section A.9.2).

Impacts of a Large Oil Spill

In the event of a large spill from a blowout, the main safety and health concerns are those of the 

offshore personnel involved in the incident and those responding to the spill. The proposed 

activities will be covered by the OSRP, and, in addition, the drilling rig maintains a Shipboard Oil 

Pollution Emergency Plan as required under MARPOL 73/78. 

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, the 

meteorological and oceanographic conditions at the time, and the effectiveness of spill response 

measures, the public could be exposed to oil on the water and along the shoreline through skin 

contact or inhalation of VOCs. Crude oil is a highly flammable material, and any smoke or vapors 

from a crude oil fire can cause irritation. Exposure to large quantities of crude oil may pose a 

health hazard. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on public health and safety are expected. 

C.8.3 Employment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and 

infrastructure. The project involves drilling with support from existing shore-based facilities in 

Louisiana. No new or expanded facilities will be constructed, and no new employees are 

expected to move permanently into the area. The project will have a negligible impact on 

socioeconomic conditions such as local employment, existing offshore and coastal infrastructure 

(including major sources of supplies, services, energy, and water), and minority and lower 

income groups. Impacts of a small fuel spill and a large oil spill are addressed below. 

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts. DOCD Section 9b provides detail on spill 

response measures. Given the open ocean location of the lease area, the duration of a small spill 

and opportunity for impacts to occur would be very brief. 

A small fuel spill that is dissipated within a few days would have little or no economic impact, as 

the spill response would use existing facilities, resources, and personnel. 

Impacts of a Large Oil Spill

Potential socioeconomic impacts of an oil spill are discussed in MMS (2007b) and BOEM (2012b,c, 

2013). For this DOCD, there are no unique site-specific issues with respect to employment and 

coastal infrastructure. A large spill could cause several types of economic impacts: extensive 

fishery closures could put fishermen out of work; temporary employment could increase as part 

of the response effort; adverse publicity could reduce employment in coastal recreation and 

tourism industries; and OCS drilling activities, including service and support operations that are 

an important part of local economies, could be suspended. 

The lease area is 84 miles (135 km) from the nearest shoreline. Based on the OSRA modeling 

predictions (Table 3), Louisiana and Florida coastal areas are the most likely to be contacted by 

a spill. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on employment and infrastructure are expected. 

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C.8.4 Recreation and Tourism

BOEM has reexamined the analyses for recreation and tourism presented in MMS (2007b) based 

on additional information and in consideration of the Macondo oil spill event. No new information 

was found that would alter the potential impacts on recreation and tourism (BOEMRE, 2011; 

BOEM, 2012c, 2013).

There are no known recreational uses of the lease area. Recreational resources and tourism in 

coastal areas would not be affected by routine activities due to the distance from shore. 

Compliance with NTL 2012-BSEE-G01 will minimize the chance of trash or debris being lost 

overboard from the drilling rig and subsequently washing up on beaches. 

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP 

will mitigate and reduce the potential for impacts. DOCD Section 9b provides detail on spill 

response measures. Given the open ocean location of the lease area, the duration of a small spill 

and opportunity for impacts to occur would be very brief. 

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are 

no known recreational or tourism activities occurring in the lease area, and as explained in 

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

prior to breaking up. 

Impacts of a Large Oil Spill

Potential impacts of an oil spill on recreation and tourism are discussed in MMS (2007b) and 

BOEM (2012a,b,d, 2013). For this DOCD, there are no unique site-specific issues with respect to 

these impacts. 

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate 

including the effectiveness of response measures. A large spill that reached coastal waters and 

shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, 

resulting in negative publicity that encourages people to stay away. Based on OSRA modeling as 

summarized in Table 3, Plaquemines Parish, Louisiana, is the area most likely to be contacted by 

a spill. However, shorelines from Cameron Parish, Louisiana, to the Florida Panhandle could be 

contacted. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on recreation and tourism are expected. 

C.8.5 Land Use

Land use along the northern Gulf Coast is discussed in MMS (2007b) and BOEM (2012b,c, 2013). 

There are no routine IPFs potentially affecting land use. The project will use existing onshore 

support facilities in Louisiana. The land use at the existing shore base sites is industrial. The 

project will not involve new construction or changes to existing land use and, therefore, will not 

have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and 

services including scarce coastal resources, will represent a small fraction of the level of activity 

occurring at the shore bases. 

A large oil spill is the only relevant accident IPF. A small fuel spill would not have impacts on 

land use, as the response would be staged out of existing shore bases and facilities. 

Impacts of a Large Oil Spill

The initial response for a large oil spill would be staged out of existing facilities, with no effect on 

land use. A large spill could have limited temporary impacts on land use along the coast if 

additional staging areas were needed. For example, during the Macondo spill, 25 temporary 

staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response 

and cleanup efforts (BOEM, 2012b). In the event of a large spill in the lease area, similar 

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temporary staging areas could be needed. These areas would eventually return to their original 

use as the response is demobilized. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on land use are expected. 

C.8.6 Other Marine Uses

The lease area is not located within any USCG-designated fairway or shipping lane. MC 657 is 

located within Eglin Water Test Area 1. Shell will comply with BOEM requirements and lease 

stipulations to avoid impacts on uses of the area by military vessels and aircraft. 

Proposed wellsites C-4 and C-5 will be located approximately 250 ft (76 m) northeast of Shell’s 

existing Coulomb prospect flowlines. The shallow hazards assessment concludes that the 

proposed wellsites will not interfere with the existing flowlines. 

There are no IPFs from routine project activities that are likely to affect shipping or other marine 

uses. A large oil spill is the only relevant accident IPF. A small fuel spill would not have impacts 

on other marine uses, as the spill and response activities would be mainly within the lease area 

and the duration would be brief. 

Impacts of a Large Oil Spill

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The 

lease block is not located within any USCG-designated fairway or shipping lane. In the event of a 

large spill requiring numerous response vessels, coordination would be required to manage the 

vessel traffic for safe operations. Shell will comply with BOEM requirements and lease 

stipulations to avoid impacts on uses of the area by military vessels and aircraft. 

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

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

DOCD Section 2j. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate 

and reduce the impacts. DOCD Section 9b provides detail on spill response measures. 

Therefore, no significant spill impacts on other marine uses are expected. 

C.9 Cumulative Impacts

For purposes of NEPA, cumulative impact is defined as “the impact on the environment which 

results from the incremental impact of the action when added to other past, present, and 

reasonably foreseeable future actions regardless of what agency (federal or non-federal) or 

person undertakes such other 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 may result. 

Prior Studies. Prior to the lease sales, MMS prepared a multisale EIS in which it analyzed the 

environmental impact of activities that might occur in the multi-lease-sale area. MMS and BOEM 

also analyzed the cumulative impacts of OCS development activities similar to those planned in 

this DOCD in several documents. The level and types of activities planned in Shell's DOCD are 

within the range of activities described and evaluated in the Final EIS for Gulf of Mexico OCS Oil 

and Gas Lease Sales 2007-2012: Western Planning Area Sales 204, 207, 210, 215, and 218, and 

Central Planning Area Sales 205, 206, 208, 213, 216, and 222 (MMS, 2007b), as updated by a 

2012 Final Supplemental EIS for Gulf of Mexico OCS Oil and Gas Lease Sales 2012-2017: Western 

Planning Area Lease Sales 229, 233, 246, and 248 and Central Planning Area Lease Sales 227, 

231, 235, 241 and 247 (BOEM, 2012b) and the Final Programmatic EIS for OCS Oil and Gas 

Leasing Program: 2012-2017 (BOEM, 2012a) and the Final Supplemental EIS for Gulf of Mexico 

OCS Lease Sales 2013-2014: Western Planning Area Lease Sale 233 and Central Planning Area 

Lease Sale 231 (BOEM, 2013). Past, present, and reasonably foreseeable activities were 

identified in the cumulative effects scenario of these documents, which are incorporated by 

reference. The proposed action will not result in any additional impacts beyond those evaluated 

in the Multisale, Final EISs, and Programmatic EIS (MMS, 2007b; BOEM, 2012a,b, 2013). 

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Description of Activities Reasonably Expected to Occur in the Vicinity of Project Area. Other 

exploration and development activities may occur in the vicinity of lease block MC 657. Shell 

does not anticipate other projects in the vicinity of the project area beyond the types of projects 

analyzed in the Multisale, Supplemental, and Programmatic EISs (MMS, 2007b; BOEM, 2012a,b,c, 

2013). 

Cumulative Impacts of Activities in the DOCD. The MMS (2007b) multi-lease-sale EIS and 

BOEM (2012b,c) Final EISs included a lengthy discussion of cumulative impacts, which analyzed 

the environmental and socioeconomic impacts from the incremental impact of the 11 proposed 

lease sales, in addition to all activities (including non-OCS activities) projected to occur from past, 

proposed, and future lease sales during the 40-year period of 2007 to 2046 (see MMS, 2007b; 

BOEM, 2012b). The EIS considered exploration, delineation, and development wells; platform 

installation; service-vessel trips; and oil spills. The EIS examined the potential cumulative effects 

on each specific resource for the entire Gulf of Mexico. 

The level and type of activity proposed in Shell’s DOCD are within the range of activities 

described and evaluated in the recent multi-lease-sale EISs. This EIA incorporates and builds on 

these analyses by examining the potential impacts on physical, biological, and socioeconomic 

resources from the work planned in this DOCD, in conjunction with the other reasonably 

foreseeable activities expected to occur in the Gulf of Mexico. Thus, for all impacts, the 

incremental contribution of Shell’s proposed actions to the cumulative impacts analysis in these 

prior analyses is not significant. 

C.9.1 Cumulative Impacts to Physical/Chemical Resources

The work planned in this DOCD is limited in geographic scope and duration, and the impacts on 

the physical/chemical environment will be correspondingly limited. 

Air Quality. Emissions from pollutants into the atmosphere from activities are not projected to 

have significant effects on onshore air quality because of the prevailing atmospheric conditions, 

emission rates and heights, and resulting pollutant concentrations. As BOEM found in the 

multi-lease-sale EISs, the incremental contribution of activities similar to Shell’s proposed 

activities to the cumulative impacts is not significant and will not cause or contribute to a 

violation of national ambient air quality standard (MMS, 2007b; BOEMRE, 2011; BOEM, 2012b). 

In addition, the cumulative contribution to visibility impairment is also very small (MMS, 2007b, 

2008; BOEMRE, 2011; BOEM, 2012b). As mentioned in previous sections, projected emissions 

meet the BOEM exemption criteria and would not contribute to cumulative impacts on air quality. 

Climate Change. Carbon dioxide (CO2) and CH4 emissions from the project would constitute a 

negligible contribution to greenhouse gas emissions from all OCS activities. According to BOEM 

(2013), greenhouse gas emissions from all OCS oil and gas activities make up a very small 

portion of national CO2 emissions and BOEM does not believe that emissions directly attributable 

to OCS activities are a significant contributor to global greenhouse gas levels. Greenhouse gas 

emissions from the DOCD 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 taking action in four areas: producing more natural gas, the cleanest-burning fossil fuel; 

helping to develop technologies to capture and store CO2; producing low-carbon biofuel; and 

working to improve the energy efficiency of our operations (Shell, 2012) 

Water Quality. Shell’s project will result in some minor water quality impacts due to the 

NPDES-permitted discharge of SBM cuttings, treated sanitary and domestic wastes, excess 

cement, non-contact cooling water, deck drainage, desalination unit brine, uncontaminated fire 

water and ballast water. These effects are expected to be minor (localized to the area within a 

few hundred meters of the drilling rig), and temporary (lasting only hours longer than the 

disturbance or discharge). Any cumulative effects to water quality are expected to be negligible. 

Archaeological Resources. MC 657 is on the list of archaeology survey blocks (BOEM, 2012c). 

Archaeological assessments by Marmaduke & Associates, LLS (2005) and C&C Technologies, Inc. 

(2006) indicated the presence of 37 sonar contacts, one of which is confirmed to be a historic 

shipwreck with an existing 2,000-ft (610-m) avoidance zone. Also, the lease area is well beyond 

the 197-ft (60-m) depth contour used by BOEMRE as the seaward extent for prehistoric 

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archaeological site potential in the Gulf of Mexico. Therefore, Shell’s routine operations should 

have no cumulative impacts on historic shipwrecks or prehistoric archaeological resources. 

New Information. New information included in the most recent Programmatic, Supplemental, 

and Final EISs (BOEMRE, 2011; BOEM, 2012a,b,d, 2013) has been incorporated into the EIA, 

where applicable. 

C.9.2 Cumulative Impacts to Biological Resources

The work planned in this DOCD is limited in geographic scope and duration, and the impacts on 

biological resources will be correspondingly limited. 

Seafloor Habitats and Biota. Effects on seafloor habitats and biota from discharges of drilling 

mud and cuttings are expected to be minor and limited to a small area. White et al. (2012) 

observed dead and damaged deepwater corals approximately 7 miles (11 km) southwest of the 

Macondo wellhead. The researchers concluded, based on hopanoid petroleum biomarker 

analysis of the flocculent material, that it contained oil from the Macondo spill. The impacted 

corals are located approximately XYZ miles (XYZ km) west-southwest of MC657, in substantially 

shallower water (4,600 ft [1,400 m]) than is found at the proposed wellsites 7,553 ft (2,302 m). 

It is unlikely that there would be cumulative impacts to those corals even in the unlikely event of 

a large spill associated with the activities discussed in this EIA. 

It is unlikely that there would be cumulative impacts to those corals even in the unlikely event of 

a large spill associated with the activities discussed in this EIA. 

Areas that may support high-density deepwater benthic communities will be avoided as required 

by NTL 2009-G40. Soft bottom communities are ubiquitous along the northern Gulf of Mexico 

continental slope, and the extent of benthic impacts during this project is insignificant regionally. 

As noted in the multi-lease-sale EISs, the incremental contributions of activities similar to Shell’s 

proposed activities to the cumulative impacts is not significant (MMS, 2007b; BOEM, 2012b,c). 

Threatened, Endangered, and Protected Species. Threatened and endangered species 

reasonably likely to occur in the lease area include the sperm whale and five species of sea turtle. 

Potential impact sources include drilling rig presence (including noise and lights), marine debris, 

and support vessel and aircraft traffic. Potential effects for these species would be limited and 

temporary, and would be reduced by Shell’s compliance with BOEM-required mitigation measures 

including NTLs 2012-BSEE-G01 and 2012-JOINT-G01. No significant cumulative impacts are 

expected. 

Coastal and Marine Birds. Birds may be exposed to contaminants including air pollutants and 

routine discharges, but significant impacts are unlikely due to rapid dispersion. Shell’s 

compliance with NTL 2012-BSEE-G01 will minimize the likelihood of debris-related impacts on 

birds. Support vessel and helicopter traffic may disturb some foraging and resting birds; 

however, it is likely that individual birds would experience, at most, only short-term behavioral 

disruption. 

Due to the limited scope, duration, and geographic extent of drilling activities, collisions or other 

adverse effects are unlikely, and no significant cumulative impacts are expected. 

Fisheries Resources. Exploration and production structures occur in the MC lease blocks 

proposed for the drilling activities. The additional effect of the proposed drilling activity would be 

negligible. 

Coastal Habitats. Due to the distance of the wellsites from shore, routine activities are not 

expected to have any impacts on beaches and dunes, wetlands, seagrass beds, coastal wildlife 

refuges, wilderness areas, or any other managed or protected coastal area. The support bases 

at Port Fourchon and Amelia, Louisiana are not in wildlife refuge or wilderness areas. Support 

operations, including the crew boat and supply boats, may have a minor incremental impact on 

coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode 

shorelines along inlets, channels, and harbors. Impacts will be minimized by following the speed 

and wake restrictions in harbors and channels. 

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New Information. New information included in the most recent Programmatic, Supplemental, 

and Final EISs (BOEMRE, 2011; BOEM, 2012a,b,c, 2013) has been incorporated into the EIA, 

where applicable. 

C.9.3 Cumulative Impacts to Socioeconomic Resources

The work planned in this DOCD is limited in geographic scope and duration, and the impacts on 

socioeconomic resources will be correspondingly limited. 

The multi-lease-sale, supplemental, and final EISs analyzed the cumulative impacts of oil and gas 

exploration and development in the lease area, in combination with other impact-producing 

activities, on commercial fishing, recreational fishing, recreational resources, historical and 

archaeological resources, land use and coastal infrastructure, demographics, and environmental 

justice (MMS, 2007b; BOEM, 2012b,c). BOEM also analyzed the economic impact of oil and gas 

activities on the Gulf states, finding only minor impacts in most of Texas, Mississippi, Alabama, 

and Florida; more significant impacts in parts of Texas; and substantial impacts in Louisiana. 

Shell’s proposed activities will have negligible cumulative impacts on socioeconomic resources. 

There are no IPFs associated with routine operations that are expected to affect public health 

and safety, employment and infrastructure, recreation and tourism, land use, or other marine 

uses. Due to the distance from shore, it is unlikely that any recreational fishing activity is 

occurring in the project area, and it is unlikely that any commercial fishing activity other than 

longlining occurs at or near the project area. The project will have negligible impacts on fishing 

activities. 

New Information. New information included in the most recent Programmatic, Supplemental, 

and Final EISs (BOEMRE, 2011; BOEM, 2012a,b,d, 2013) has been incorporated into the EIA, 

where applicable. 

D. Environmental Hazards 

D.1 Geologic Hazards

The shallow hazards assessment included in this DOCD, based on the archaeological and cultural 

resource assessments by Marmaduke & Associates, LLS (2005) and C&C Technologies, Inc. 

(2006), concludes that the wellsites are free of any major geological hazards and are suitable for 

the proposed activities. There are no amplitude or fluid expulsion features, seafloor or nearsurface slumping, or faulting within 2,000 ft (600 m) of the proposed well locations or within the 

15,000-ft generic anchor radius for the proposed wellsites, based on results of a high-resolution 

geophysical survey consisting of autonomous underwater vehicle (AUV) and deep-tow side-scan 

sonar, and subbottom profiling. 

See DOCD Section 6a for supporting geological and geophysical information. 

D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. 

Extreme weather, including high winds, strong currents, and large waves, was considered in the 

design criteria for the drilling rig. High winds and limited visibility during a severe storm could 

disrupt communication and support activities (vessel and helicopter traffic) and make it necessary 

to suspend some activities on the drilling rig for safety reasons until the storm or weather event 

passes. In the event of a hurricane, procedures in Shell’s Hurricane Evacuation Plan would be 

followed. 

D.3 Currents and Waves

A rig-based acoustic Doppler current profiler will be used to continuously monitor the current 

beneath the rig. Metocean conditions such as sea states, wind speed, and ocean currents also 

will be continuously monitored. Under most circumstances, physical oceanographic conditions 

are not expected to have any effect on the proposed activities. Strong currents (e.g., caused by 

Loop Current eddies and intrusions) and large waves were considered in the design criteria for 

the drilling rig. High waves during a severe storm could disrupt support activities (i.e., vessel and 

Page 166 Public Information Copy
helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety 

reasons until the storm or weather event passes. 

E. Alternatives 

No formal alternatives were evaluated in this EIA. However, various technical and operational 

options, including the location of the wellsites and the selection of a drilling unit, were considered 

by Shell in developing the proposed action. There are no other reasonable alternatives to 

accomplish the goals of this project. 

F. Mitigation Measures 

The proposed action includes numerous mitigation measures required by laws, regulations, and 

BOEM lease stipulations and NTLs. The project will comply with applicable federal, state, and 

local requirements concerning air pollutant emissions, discharges to water, and solid waste 

disposal. Project activities will be conducted under Shell’s OSRP and will include the measures 

described in DOCD Section 2f.

G. Consultation 

No persons or agencies were consulted regarding potential impacts associated with the proposed 

activities during the preparation of this EIA. 

H. Preparers 

The EIA was prepared at the direction of Shell Offshore Inc. by its contractor, 

CSA Ocean Sciences Inc. Contributors included the following: 

Tracy Albert (Regulatory Specialist, Regulatory Compliance Consultants of LA, LLC); 

Jeffrey McMenis (Environmental Engineer, Shell Exploration & Production Co.); 

Mark Koper (Well Development Team Lead, Shell Exploration & Production Co.); 

Megan Henley (Drilling Engineer, Shell Exploration & Production Co.); 

June Mire, Ph.D. (Senior Ecologist and Project Manager, Tetra Tech EM, Inc.); 

Carlyle Kalloo (Senior Scientist, CSA Ocean Sciences Inc.); 

John Thompson (Senior Scientist, CSA Ocean Sciences Inc.); 

Neal Phillips, Ph.D. (Senior Scientist, CSA Ocean Sciences Inc.); 

Deborah Fawcett (Project Scientist, CSA Ocean Sciences Inc.); 

John Tiggelaar II (Project Scientist, CSA Ocean Sciences Inc,); 

Keith VanGraafeiland (GIS/Remote Sensing Specialist, CSA Ocean Sciences Inc.); and 

Natalie Kraft (Technical Editor, CSA Ocean Sciences Inc.). 

Page 167 Public Information Copy
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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 

2c. Production Information 

3A and 3B. Geologic Description 

3b. Structure Contour Maps 

3C. Interpreted 2D or 3D seismic line(s) 

3D. Cross Section(s) 

3E. Top hole prognosis and power spectrum diagram 

4b. H2S Classification Information 

5. Mineral Resource Conservation information 

B. Bibliography 

McClelland Engineers, Shallow Hazards Report, Blocks 612, 613, 656, and 657, Mississippi Canyon Area, 

Gulf of Mexico, Project No. 0186-2068, dated December 18, 1986. Data includes: Sparker, Deep tow 

side-scan sonar and sub-bottom profiler. (C targets) 

GEMS, Inc., Geologic and Stratigraphic Assessment, Block 701 (OCS G-21183) Mississippi Canyon Area, 

Gulf of Mexico, Project No. 0605-1004, dated October 10, 2005. Data includes: 3-D Seismic and Deeptow side-scan sonar and sub-bottom profiler. (SC targets) 

C&C Technologies. AUV Hazard Study, Blocks 657 (OCS-G-09496), 701 (OCS-G-21183), Mississippi 

Canyon Area, and 617 (CS-G-23525) and 661 (Unleased), Desoto Canyon Area, Project No. 061829, 

dated January 2007. Data includes: AUV side-scan sonar and sub-bottom profiler. (DC617-2006 targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 617 

(Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. Data 

includes: 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 targets) 

Marmaduke & Assoc, LLS. Cultural Resource Evaluation, Mississippi Canyon Blocks 612, 613, 656, 657, & 

701, dated August 2005. Data includes: Deep-tow side-scan sonar and sub-bottom profiler. (C targets) 

C&C Technologies. Archaeological Assessment “Shallow Coulomb” Prospect, Blocks 657 (OCS-G-09496), 

701 (OCS-G-21183), Mississippi Canyon Area, and 617 (CS-G-23525), and 661 (Unleased), Desoto 

Canyon Area, Project No. 061829, dated December 2006. Data includes: AUV side-scan sonar and subbottom profiler. (DC617-2006 targets) 

GEMS, Inc., Geologic, Stratigraphic and Archaeological Assessment of Blocks 573 (OCS G 23521 and 617 

(Open), De Soto Canyon Area, Gulf of Mexico, Project No. 0313-2213a,b, dated July 25, 2013. Data 

includes: Re-processed 3-D seismic, AUV side-scan sonar and sub-bottom profiler. (DC573-2013 targets) 

GEMS, Inc. Geologic, Stratigraphic, and Archaeological Assessment of Block 566 (OCS-G 8831), 567 

(OCS-G 33744), 611 (OCS-G 27287) 612 (OCS-G 33166) and 656 (OCS-G 33752), Mississippi Canyon 

Area, Gulf of Mexico, Project Number 0811-1984a, August 22, 2012. 

Shell Regional OSRP, 2013 

Shell DOCD’s N-7527 & R-3944 

EIA prepared by CSA International, Inc. 

Page 176 Public Information Copy