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6) Response 

ExxonMobil has contracted with Marine Spill Response Corporation (MSRC) and Clean Gulf 

Associates (CGA) as primary Oil Spill Removal Organizations. Contact information for both OSROs can 

be found in Figure 7-2 of the oil spill response plan. Upon notification of the spill, ExxonMobil would 

request mobilization from the resources identified in the Appendix E of the oil spill response plan. 

An Adios 2 model was run on a similar product. The results indicate 19% of the product would be 

evaporated or naturally dispersed within 24 hours, leaving approximately 142,475 bbls on the water. 

Sample Rescouce Response Status Boards above outline skimming equipment as well as 

temporary storage equipment to be considered in order to cope with an initial spill of 175,895 bbls. 

The list estimates individual times needed for procurement, load out, travel time to the site and 

deployment. 

Upon notification of the spill, ExxonMobil would request a partial or full mobilization of resources, 

including, but not limited to, MSRC and/or CGA skimming vessels and dispersant aircraft available from 

Airborne Support, Inc. (ASI) through memberships with MSRC and CGA. Aerial dispersant aircraft 

available from CCA may also be called depending on oil spill severity. The Qualified Individual, Person 

in Charge, Incident Commander or designee may contact other service companies if the Unified 

Command deems such services necessary to the response effort. 

Simultaneous operations (SIMOPS) may involve different companies working in close proximity on 

identical and/or different tactical objectives. SIMOPS may include but are not lmited to subsea 

operations, surface operations or a combination of both. These operations must be well planned and 

coordinated. SIMOPS will be evaluated daily and coordinated based on the response efforts needs, as 

well as, additional criteria (e.g. meteorological conditions, sea state, etc.). Regular communications 

will be established and maintained during all SIMOPS activities. 

SIMOPS activities may include but are not limited to the following:

 Dispersant Application (Aerial and/or Vessel), if approved.

 In-situ Burning

 Mechanical Recovery

 Nearshore / Shoreline Response

 Source Control / Subsea Operations

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Offshore Response 

Primary offshore response would involve mechanical recovery. Offshore response strategies may 

include attempting to skim utilizing an MSRC Responder Vessel, Oil Spill Response Barges (OSRBs), 

Vessel of Opportunity (VOOs), Boats, and Fast Response Units. Other technologies (like GPS-based 

vessel tracking systems) may be used to facilitate coordination of marine resources. This equipment 

may be facilitated by air-based spotters that can guide these systems to oil concentrations. During 

night-time operations, skimming activities could be facilitated through the use of alternative spill 

surveillance technologies (such as infrared [IR] and X-band radio systems) to guide skimming vessels to 

sufficient concentrations of oil. The specific technologies used will be chosen based on availability, 

suitability, OSRO recommendations, and other considerations that are specific to the situation. 

Offshore response strategies include, but are not limited, to the following:

• Mobilize mechanical recovery resources, including vessels (both OSRVs and 

VOOs), barges, ocean boom, skimming equipment, and spotter/surveillance 

aircraft. Begin deploying mechanical recovery resources as close to the source as 

possible to contain and collect concentrated oil in a timely, and effective manner. 

Radio communications will be established between spotter aircraft and other 

surveillance systems (including AIS) with skimming vessels and barges to direct 

vessels to locations of concentrated oil to ensure maximum effectiveness and 

efficiency of mechanical recovery equipment. 

• Mobilize dispersant resources to pre-approved and approved locations for both 

aerial and boat application, in areas where oil cannot be mechanically recovered. 

Subsea dispersant application equipment may be mobilized at the discretion of 

the RRT, and requires approval from the RRT. If approved, subsea dispersant 

application with be in accordance with RRT 6 guidelines. 

• Mobilize in-situ burn resources outside the vicinity of the source to collect and 

burn oil in heavily concentrated locations. Fire boom will be deployed in a Uconfiguration 

• Mobilize offshore vessels equipped with remote sensing technologies (radar, 

infrared camera) to aid in night time operations and slick tracking. Remote 

sensing technologies assist skimming vessels in identifying thick areas of oil to 

enhance encounter rate and Estimated Derated Receovery Capacity (EDRC). 

• Maintain an effective and well coordinated response effort for the length of time 

to control the source of the discharge, which may involve drilling a relief well, 

and up to the point when the Federal On-Scene Coordinator determines the 

response effort complete. 

Mechanical oil spill response uses physical barriers (boom) and mechanical devices (skimmers) to 

redirect and remove oil from the surface of the water. 

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Mechanical cleanup strategies include, but are not limited, to the following:

• Skimming systems will deploy boom in a variety of different configurations. 

Generally, boom will be deployed in a J-configuration in a single skimming unit, 

which requires only one assist vessel to attend the boom. These single skimming 

units will locate heavily concentrated oil, with assistance from spotters and 

remote sensing technologies, to ensure enhanced encounter rate and effective 

recovery. Boom will be deployed in a U-configuration when skimming vessels or 

barges have access to two assist vessels. This configuration maximizes the swath 

width and containment capacity. Boom may be deployed in a U-configuration 

with an open apex to funnel oil to awaiting skimming vessels. 

• Vessels of opportunity (VOO) equipped with skimming systems will be deployed 

to locations of recoverable oil. For locations with light oil that cannot be 

recovered mechanically, vessels of opportunity will be equipped with sorbent 

materials to recover this light oil. 

• In order to increase encounter rate, slick containment systems will be directed to 

locations of heavily concentrated oil from spotter aircraft and vessels with 

remote sensing technology. Once the oil has been contained within the booms, 

the oil is dumped into the path of a skimming vessel. Boom also may be 

configured into a U-configuration with an open apex to funnel oil to awaiting 

skimming vessels. 

• Oil that escapes the above assets and moves shoreward will be collected by 

vessels of opportunity that deploy sorbent boom, collection nets or other types 

of equipment that absorbs surface oil. These assets will be deployed as task 

forces that can rapidly respond to light oil. 

Current proven and available sensing technology for tracking oil at night includes hand held, boat 

mounted and aircraft mounted infrared sensing. ExxonMobil understands that multiple new oil 

sensing technologies (radar, satellite imagery, fluorometry, etc.) are being reviewed and developed by 

the industry and as they become more mature, proven and available to the industry, ExxonMobil will 

work with OSROs to include these improvements in our response capability. These and any other new 

oil sensing technologies that become available will be deployed with the purpose of improving the 

ability of keeping deployed oil skimming platforms in the most highly concentrated areas of spilled oil 

and may be used to potentially improve the capabilities to skim beyond traditional daylight hours. 

However the latter capability can only be implemented taking all aspects of safe operations in account 

and ensuring that there is no additional risk to human life. 

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Depending on proximity to shore and water depth, dispersants from aerial and vessel applications 

may be viable response options and will require the appropriate approvals as outlined in Section 18, 

Dispersant Use Plan. Aerial application will consist of 3 to 4 sorties from ASI’s three DC-3’s and one 

DC-4. In addition, spotter aircraft could be activated along with the aerial dispersant aircraft to assist in 

a more precise dispersant application. Assuming a 1:20 application rate, 90% effectiveness, and 3-4 

sorties per day, the ASI aerial systems could disperse approximately 5,658 to 7,543 barrels of oil per 

day. Additionally, subsea dispersant application and boat spray application are other methods for 

applying dispersants. Subsea dispersant application requires approval from the appropriate RRT. 

A list of available dispersant stockpiles is located in Section 18, Dispersant Use Plan. Additional 

dispersant supplies are available and may be acquired from other sources through industry 

agreements at the direction of the FOSC and appropriate RRT. Priorities for dispersant use and 

rationing of existing supplies will be determined on an incident specific basis to allow for maximum 

effectiveness of dispersants. Dispersant use will be dictated by approval, safety, weather, and sea 

states before application and coordinated with Unified Command. In addition, ExxonMobil will assess 

the situation and can make notification within 48 hours of the initial spill to begin ramping up 

dispersant production through Nalco, as discussed in Section 18, Dispersant Use Plan. 

ExxonMobil has contracted with Marine Well Containment Company for a subsea dispersant 

package. Subsea dispersant application has been found to be highly effective at reducing the amount 

of oil reaching the surface; however, approval is required from the appropriate Regional Response 

Team (RRT) prior to use. Additional data collection, laboratory tests and field tests will help in 

facilitating the optimal application rate and effectiveness numbers. For planning purposes, 

ExxonMobil assumes a 1:100 application rate, at 90% effectiveness (based on accepted industry 

dispersant effectiveness standards), and a system flow rate of 8-11 gallons per minute (approximately 

11,500 to 16,000 gallons of dispersant per day). Using these assumptions, the system has the 

potential to disperse approximately 24,500 to 34,000 barrels of oil per day. 

Dispersant use will be dictated by approval, safety, weather, and sea states before application and 

coordinated with Unified Command. In addition, ExxonMobil will assess the situation and can make 

notification within 48 hours of the initial spill to begin ramping up dispersant production through 

Nalco. 

All dispersant applications will be in compliance with RRT 6 guidelines. 

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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 

up to 8 burns before being replaced. Fire intensity and weather will be the main determining factors 

for actual burns per system. Although the actual amount of oil that will be removed per burn is 

dependent on many factors, recent data suggests that a typical burn might eliminate approximately 

750 barrels. For planning purposes and based on the above assumptions, a single task force of four 

fire teams with the appropriate weather and safety conditions could complete four burns per day and 

remove up to ~12,000 bbls/day. In-situ burning nearshore and along shorelines may be a possible 

option based on several conditions and with appropriate approvals, as outlined in Section 19, In-situ 

Burn Plan. In-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. Additional 

information on ISB is presented in Section 19, In-situ Burn Plan. In addition, ExxonMobil 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) as discussed in Section 19, In-situ Burn Plan. 

Slick (fresh oil) containment systems may be deployed (provided it is safe to do so) in thick, fresh 

oil to minimize further spreading of oil on the water’s surface. These systems would typically consist of 

two offshore vessels (capable of trolling speeds of 0.5 knots) towing between 1,000 to 1,500 feet of 

offshore boom in a “U” or “V” configuration. The containment systems would allow fresh oil to be 

contained, concentrated and diverted to skimming systems and/or in-situ burn task forces, increasing 

their encounter rate and containment efficiency in order to support enhanced skimming and burning 

operations. 

The initial response to a well blowout would be an attempt to activate the blowout preventers 

and close the well. The Source Control team will be stood up immediately. The primary well control 

provider, Marine Well Containment Company (MWCC), would be notified in the event of a blowout. 

The first step will be determining if the well can be capped and killed. If the well cannot be capped, the 

relief well(s) operations may start as soon as possible. 

Subsea containment resources would be mobilized in the event of an uncontrolled well blowout. 

Subsea containment incorporates simultaneous operations to cap or contain the flow of oil within the 

well, contain the oil outside of the well and collect at surface facilities or vessels and chemically 

disperse the oil at the well head. MWCC has been contracted to supply the subsea dispersant 

applications. 

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Source control activities include, but are not limited, to the following:

• Notifications to regulatory authorities, MWCC, and support contractors 

regarding well control incident 

• Site assessment, initial response, and well monitoring

• Notification and activation of any equipment and contract services outside of 

MWCC will be initiated by ExxonMobil (e.g. shuttle tankers, helicopters, etc.) 

• Notification, as needed, to members of MWCC to assist ExxonMobil’s Source 

Control Group during source control operations 

• Debris Removal and Lower Marine Riser Package (LMRP) Recovery 

Considerations, if applicable 

• Coordination of ROVs, support vessels, intervention vessels, subsea dispersant 

equipment, debris removal tools, umbilical, chemical delivery, pumping 

services, and other equipment for WCD scenarios 

• Run Intervention Riser System

• Well Capping and Shut-in Operation Activities

In the unlikely event of a well control issue, ExxonMobil, as a member of the Marine Well Containment 

Company (MWCC), has access to an Interim Containment Response System (ICRS) that can be rapidly mobilized 

through the MWCC. The ICRS consists of equipment to contain and capture a hydrocarbon release from a 

damaged deepwater well. The primary component of the ICRS for well control is the capping stack. Additional 

components include a subsea dispersant application system, hydrate inhibition system, and a “top hat” 

(designed to recover discharged oil). MWCC will provide containment response support through a combination 

of equipment and services (owned, via mutual aid commitments, or through agreements with MWCC). Under 

direction of ExxonMobil, MWCC will participate with the response team to support direction of MWCC 

equipment and tools. 

For additional detailed information on these systems, their components, and deployment times, refer to the 

current Marine Well Containment Company Interim Containment Response System Functional Specifications 

USWC-ED-BPFEP-000001 provided to BSSE by MWCC. Information on how these systems will be deployed to 

respond to a specific well, can be found in the NTL 2010-N10 information submitted as a supplement to the 

individual “Application for Permit to Drill”. Refer to Section 6 for further details regarding Source Control. 

Nearshore and Shoreline Protection 

Potential shoreline impact 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. 

Sorbent boom is a readily available resource and can be acquired as needed. MSRC and CGA have resources 

which can be deployed for a shoreline cleanup effort (equipment locations are depicted on the MSRC and CGA 

Equipment Location map), as well as the contractor Shoreline Protection & Wildlife Support status board in this 

section. 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 Area Contingency Plan, The Response Group and Unified Command would be consulted 

to ensure that environmental and special economic resources would be correctly identified and prioritized to 

ensure optimal protection. The Response Group’s Shoreline Response Guides depict the protection response 

modes applicable for oil spill clean-up operations. Each response mode is schematically represented to show 

optimum deployment and operation of the equipment in areas of environmental concern. Supervisory personnel 

have the option to modify the deployment and operation of equipment, allowing for a more effective response 

to site-specific circumstances. (For more information on resource identification and protection methods, see 

Section 11, Resource Identification. See Section 12, Strategic Response Planning for additional information on 

Offshore and Nearshore / Shoreline response tactics. For more information on available OSRO equipment for 

shoreline protection, see Appendix E, Response Equipment. A time frame for the mobilization of equipment is 

outlined in Section 14, Mobilization & Deployment Methods, based on equipment locations). 

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If wildlife is threatened due to a spill, MSRC and CGA have resources available to ExxonMobil. These 

resources can be utilized to protect and rehabilitate wildlife. Additional wildlife equipment may also be tiered in 

from OSR. See Appendix E, Response Equipment, for details on the available resources, and Section 17, Wildlife 

Rehabilitation Procedures, for further details on the protection and rehabilitation of affected wildlife and 

contacts for available wildlife protection and rehabilitation providers. 

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SECTION 10: ENVIRONMENTAL MONITORING INFORMATION 

10.1 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. ExxonMobil 

will comply with NTL 2009-G02. 

10.2 Incidental Takes 

No incidental takes are anticipated. ExxonMobil 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” 

10.3 Flower Garden Banks National Marine Sanctuary 

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

Stetson Bank. 

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SECTION 11: LEASE STIPULATIONS INFORMATION 

Lease OCS-G 33364 is not part of a Biological Sensitive Area, known Chemosynthetic Area, or Shipping Fairway. It is not on 

the list of areas that the BOEM has identified as having a high probability for archeological resources. 

♦ Stipulation 8: Protected Species 

This Lease Stipulation assigned to Walker Ridge Block 282 is to reduce the potential taking of federally protected species 

(e.g., sea turtles, marine mammals, Gulf sturgeon and other listed species). See Sections 6, 10 and 12 of this EP. 

♦ Marine Protected Species 

BOEM has issued Notice to Lessees NTL 2012-Joint-G02 “Implementation of Seismic Mitigation Measures and Protected 

Species Observer Program”, NTL 2012-Joint-G01 “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting” and NTL 2012-G01 “Marine Trash and Debris Awareness and Elimination” to reference measures to minimize 

or avoid potential adverse impacts to protected species (sea turtles, marine mammals, gulf sturgeon, and other federally 

protected species). See Sections 6, 10 and 12 of this EP. 

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SECTION 12: ENVIRONMENTAL MITIGATION MEASURE INFORMATION 

12.1 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 ExxonMobil policies. Project activities will be conducted in accordance with the 

Regional Oil Spill Response Plan. The EIA in Section 18 discusses impacts and mitigation measures. 

12.2 Incidental Takes 

We do not anticipate any incidental takes related to the proposed operations. ExxonMobil 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” 

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 

Information regarding Related Facilities and Operations Information, transportation systems, & produced liquid hydrocarbon 

transportation vessels are not included in this EP as such information is only necessary in the case of DOCDs. 

 

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SECTION 14: SUPPORT VESSELS AND AIRCRAFT INFORMATION

14.1 General 

Type Maximum Fuel Tank 

Storage Capacity (Gals) 

Maximum No. In Area at 

Any Time 

Trip Frequency or 

Duration 

Crew Boats 8,000 2 Twice per week 

Offshore Support Vessels 120,000 3 Twice per week 

Helicopter 764 1 Once per day 

14.2 Diesel Oil Supply Vessels 

Size of Fuel Supply 

Vessel 

Capacity of Fuel 

Supply Vessel 

Frequency of Fuel 

Transfers 

Route Fuel Supply Vessel Will 

Take 

280 foot length 100,000 gals. 1 week Port Fourchon to WR 282 

14.3 Drilling Fluids Transportation 

This information is only required for Eastern Gulf of Mexico. 

14.1 Solid and Liquid Wastes Transportation 

 See Table 7B. 

14.5 Vicinity Map 

See Attached. 

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Vicinity Map 

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SECTION 15: ONSHORE SUPPORT FACILITIES INFORMATION 

15.1 General 

Name Location Existing/New/Modified 

Fourchon Port Fourchon, LA Existing 

PHI Base Morgan City, LA Existing 

Galveston Base Galveston, TX Existing 

The proposed surface disturbances in Walker Ridge Block 282 for this plan will be located approximately 162 miles from 

the nearest Louisiana shoreline, and approximately 178 miles from the onshore support base. ExxonMobil will use the 

Port Fourchon existing dock as support base. The Fourchon facility is located on Bayou Lafourche, south of Leeville, LA 

approximately 3 miles from the Gulf of Mexico. The helicopter base will be the PHI base located in Morgan City, LA. The 

Galveston Base in Galveston, TX may be used for operations in this plan. 

15.2 Support Base Construction or Expansion 

This section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP. 

15.3 Support Base Construction or Expansion Timetable 

This section does not apply to this EP as ExxonMobil does not plan to construct a new onshore support base or 

expand an existing one to accommodate the activities proposed in this EP. 

15.4 Waste Disposal 

See Tables 7A and 7B. 

15.5 Air emissions 

Not required by BOEM GOM. 

 15.6 Unusual solid and liquid wastes 

Not required by BOEM GOM. 

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SECTION 16: SULPHUR OPERATIONS INFORMATION 

Information regarding Sulphur Operations is not included in this EP as such information is only necessary in the case of 

DOCDs. 

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SECTION 17: COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION 

LOUISIANA 

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

EXPLORATION PLAN 

Type of Plan 

 

WALKER RIDGE BLOCK 282 (OCS-G 33364) 

 

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal Resources 

Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies. 

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

EXXON MOBIL CORPORATION

Operator 

_____________________________________________ 

Bryan L. Chapman 

Certifying Official 

 04/08/2013 

Date 

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TEXAS 

COASTAL ZONE MANAGEMENT 

CONSISTENCY CERTIFICATION 

EXPLORATION PLAN 

Type of Plan 

 

WALKER RIDGE BLOCK 282 (OCS-G 33364) 

 

The proposed activities described in detail in this Plan will comply with Texas State and Local Coastal Resources 

Management Act of 1978, Coastal Resources Program, and Coastal Area Management Enforceable Policies. 

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

EXXON MOBIL CORPORATION

Operator 

_____________________________________________ 

Bryan L. Chapman 

Certifying Official 

 04/08/2013 

Date 

Page 84 Public Information Copy
Coastal Zone Management Consistency Information 

For the State of Texas 

In accordance with Subpart E of 15 CFR 903 “Consistency for Outer Continental Shelf (OCS) Exploration, 

Development and Production Activities” and as required by 15 CFR 930.58, Exxon Mobil Corporation is hereby providing 

the following information in support of the Environmental Impact Analysis submitted as Attachment 18 of our initial EP. 

15 CFR 930.58 identifies necessary data and information to be furnished to the State agency. The information is as 

follows: 

(a) CONSISTENCY CERTIFICATION

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

above-mentioned EP. 

OTHER INFORMATION

A detailed description of the proposed activities, coastal effects, and comprehensive information sufficient to 

support this Consistency Certification is presented in Section 17 of the above-mentioned EP. 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 the abovementioned EP. 

• Oil Spill Information is provided in Section 9 of the above-mentioned EP. All operations are covered by 

ExxonMobil’s Regional Oil Spill Response Plan, which has been updated (pending approval) by BSEE. The Plan is 

available upon request. 

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 Texas’ Coastal Management Program (TCMP), Title 31, Part 16, 

Chapter 501, Subchapter B:

(Category 2) 

Construction, Operation & Maintenance of Oil & Gas Exploration & Production 

Facilities 

No operations are proposed in or near any critical areas. The proposed activities are of exploration in nature, so 

no facility construction is proposed. The proposed activities are located approximately 292 miles from the Texas 

shoreline; therefore we expect no adverse impacts to CNRAs or beach access and use rights of the public. All activities 

shall be conducted in a manner that minimizes significant impacts to coastal resources. No adverse effects to Texas’ 

coastal area are expected in association with the proposed activities. 

(Category 3) 

Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and Production Activities 

No discharge of wastewater or disposal of waste from the proposed activities will occur in the Texas’ coastal zone 

area; therefore no impact to Texas’ coastal waters is expected. 

(Category 4) 

Construction and Operation of Solid Waste Treatment, Storage, and Disposal 

Facilities 

No construction of solid waste facilities or expansion of existing facilities in the coastal zone are proposed in the 

attached plan, therefore, no adverse effects on any features of Texas’ coastal zone are expected. 

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(Category 5) 

Prevention, Response, and Remediation of Oil Spills 

The proposed activities will be covered under an approved Regional Oil Spill Response Plan. The plan is 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. All involved vessels and facilities are designed to be capable of prompt 

response and adequate removal of accidental discharges of oil. In addition, the proposed activities are 292 miles from 

shore; therefore no damages to natural resources are expected as the result of an unauthorized discharge of oil into 

coastal waters. 

(Category 6) 

Discharge of Municipal and Industrial Waste Water to Coastal Waters 

No discharges from the proposed activities will occur in coastal waters. The proposed activities are 292 miles from 

Texas shore; therefore there will be no effect on coastal waters. 

(Category 8) 

Development in Critical Areas 

None of the proposed activities will occur in a critical area; therefore no effects to Texas’ coastal zone are 

expected. The activity will not jeopardize the continued existence of species listed as endangered or threatened, and 

will not result in likelihood of the destruction or adverse modification of a habitat determined to be a critical habitat 

under the Endangered Species Act. The activity will not cause or contribute to violation of any applicable surface water 

quality standards. The activity will not violate any requirement imposed to protect a marine sanctuary. 

(Category 9) 

Construction of Waterfront Facilities and Other Structures on Submerged lands 

No waterfront facilities or other structures are proposed on submerged lands in the Texas coastal zone, therefore 

the proposed activities are not expected to have any adverse impacts on submerged lands. 

(Category 10) 

Dredging and Dredged Material Disposal and Placement 

No dredging or disposal/placement of dredged material is proposed, therefore no adverse effects to coastal 

waters, submerged lands, critical areas, coastal shore areas, or Gulf beaches are expected. 

(Category 11) 

Construction in the Beach / Dune System 

The proposed activities do not include any construction projects in critical dune areas or areas adjacent to or on 

Gulf beaches, therefore, no impact to Texas’ beach or dune systems are expected. 

(Category 15) 

Alteration of Coastal Historic Areas 

The proposed activities do not include any alteration or disturbance of a coastal historic area; therefore, no 

impacts to are expected to adversely affect any historical, architectural, or archaeological site in Texas’ coastal zone. 

(Category 16) 

Transportation 

The proposed activities do not include any transportation construction projects within the coastal zone; 

therefore, no impacts to Texas’ coastal zone are expected. 

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(Category 17) 

Emission of Air Pollutants 

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. The proposed activities will occur approximately 292 miles from the Texas 

shore and will be within the exemption limits set by BOEM, therefore, no impacts to Texas’ coastal zone is 

expected. 

(Category 18) 

Appropriations of Water 

The proposed activities do not include the impoundment or diversion of state water, therefore, no impacts 

to Texas’ coastal zone is expected. 

(Category 20) 

Marine Fishery Management 

The proposed activities are located approximately 292 miles from Texas shore and are not expected to have 

any effect on marine fishery management or fishery migratory patterns within waters in the coastal zone of Texas. 

(Category 22) 

Administrative Policies 

The necessary information for applicable agencies to make an informed decision on the proposed activities 

has been provided 

In conclusion, all activities shall be consistent with Texas’ coastal management program and shall comply with 

all relevant rules and regulations. No activities are planned within any critical areas. Activities will be carried out 

avoiding unnecessary conflicts with other uses of the vicinity. 

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SECTION 18 - ENVIRONMENTAL IMPACT ANALYSIS (EIA) 

Environmental Impact Analysis 

INITIAL EXPLORATION PLAN 

Walker Ridge Block 282 (OCS-G 33364) 

Offshore Louisiana 

April 2013 

Prepared for: 

ExxonMobil Corporation 

P.O. Box 4368 

Houston, Texas 77210-4358 

Telephone: (281) 654-1941 

Prepared by: 

CSA International, Inc. 

8502 SW Kansas Avenue 

Stuart, Florida 34997 

Telephone: (772) 219-3000 

 

Page 88 Public Information Copy
Acronyms and Abbreviations 

ADIOS2 Automated Data Inquiry for Oil Spills 2 

bbl barrel 

BOEM Bureau of Ocean Energy Management 

BOEMRE Bureau of Ocean Energy Management, 

Regulation and Enforcement 

BOP blowout preventer 

B.P. Before Present 

BSEE Bureau of Safety and Environmental 

Enforcement 

CH4 methane 

CO carbon monoxide 

CO2 carbon dioxide 

CFR Code of Federal Regulations 

CGA Clean Gulf Associates 

DP dynamic positioning 

EP Exploration Plan 

EEZ Exclusive Economic Zone 

EFH Essential Fish Habitat 

EIA Environmental Impact Analysis 

EIS Environmental Impact Statement 

ESA Endangered Species Act 

FAD fish-attracting device 

FR Federal Register 

GPS global positioning system 

GMFMC Gulf of Mexico Fishery Management 

Council 

H2S hydrogen sulfide 

HAPC Habitat Area of Particular Concern 

HOSS high-volume open sea skimmer 

IPF impact-producing factor 

MARPOL International Convention for the 

Prevention of Pollution from Ships 

MMC Marine Mammal Commission 

MMPA Marine Mammal Protection Act 

MMS Minerals Management Service 

MSRC Marine Spill Response Corporation 

NAAQS National Ambient Air Quality 

Standards 

NMFS National Marine Fisheries Service 

NOAA National Oceanic and Atmospheric 

Administration 

NOx nitrogen oxides 

NPDES National Pollutant Discharge 

Elimination System 

NRDA Natural Resource Damage Assessment 

NTL Notice to Lessees and Operators 

NWR National Wildlife Refuge 

OBM oil-based mud 

OCS Outer Continental Shelf 

OSRA Oil Spill Risk Analysis 

OSRP Oil Spill Response Plan 

PAH polycyclic aromatic hydrocarbon 

PM particulate matter 

SBM synthetic-based mud 

SHL surface hole location 

SOx sulfur oxides 

SWSS Sperm Whale Seismic Study 

USCG U.S. Coast Guard 

USEPA U.S. Environmental Protection Agency 

USFWS U.S. Fish and Wildlife Service 

VOC volatile organic compound 

WCD worst case discharge 

WR Walker Ridge 

Page 89 Public Information Copy
Introduction 

ExxonMobil Corporation (ExxonMobil) is submitting an Initial Exploration Plan (EP) for Walker Ridge (WR) 

Block 282 (WR 282). The EP is for one exploratory, Well “A,” in WR 282. This Environmental Impact 

Analysis (EIA) provides information on the exploratory well based on the surface hole location (SHL). 

The lease area is 261 km (162 miles) south-southwest of the nearest shoreline and 287 km (178 miles) 

from the onshore support base and helicopter base at Port Fourchon, Louisiana (Figure 1). Water depth 

at the wellsite is approximately 1,937 m (6,354 ft). The drilling rig will be the Transocean Deepwater 

Champion or a similar dynamic positioning (DP) drillship. This EIA was prepared for submittal to the 

Bureau of Ocean Energy Management (BOEM) in accordance with applicable regulations, including 

30 Code of Federal Regulations (CFR) 550.212(o) and 550.227. The EIA is a project- and site-specific 

analysis of ExxonMobil’s planned activities under this EP and complies with guidance provided in existing 

Notices to Lessees and Operators (NTLs) issued by the former Minerals Management Service (MMS) and 

the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), including NTL 

2008-G04. Potential impacts have been analyzed at a broader level in Programmatic Environmental 

Impact Statements (EISs) for the Outer Continental Shelf (OCS) Oil and Gas Leasing Program (MMS, 2007a; 

BOEM, 2012d) and in multi-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas 

(MMS, 2007b; BOEM, 2012b). The analyses from these documents are incorporated here by reference. 

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for evaluating oil spill 

risk during exploratory drilling. According to Holand (1997), the average frequency of a loss of well 

control incident or "blowout" during exploratory drilling in the U.S. Gulf of Mexico is 0.00593 blowouts 

per well drilled, or one blowout per 169 exploration wells drilled. Similarly, the MMS Safety and 

Environmental Management Program blowout incident rate for 1996 to 1999 was approximately five 

blowouts per 1,000 well starts, or one blowout per 200 well starts (MMS, 2000). More recently, in its 

Final Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEM confirmed that "significant 

changes to the spill rates for the entire OCS are not anticipated" (BOEM, 2012b). 

Historically, most blowouts have not resulted in oil spills. Of 151 well blowouts in the Gulf of Mexico from 

1971 to 1995, only 18 (12%) resulted in oil spills, with a total combined volume of 1,000 barrels (bbl) of 

crude oil and condensate released (MMS, 2000). Between 1964 and 1999, almost all offshore spills (94%) 

from drilling and production-related operations on the OCS were ≤1 bbl in size (Anderson and LaBelle, 

2000). According to BSEE’s Final Drilling Safety Rule (75 Federal Register [FR] 63365) issued following the 

Macondo incident, the baseline risk of a catastrophic blowout is estimated to be about once every 26 

years. 

Page 90 Public Information Copy
Figure 1. Location of Walker Ridge Block 282. 

Page 91 
ExxonMobil’s Regional Oil Spill Response Plan (OSRP) was originally approved by the MMS on 

7 December 2009. A revised and updated OSRP was submitted to BOEM in December 2010, July 2011, 

and December 2011, and pending approval. The OSRP details ExxonMobil’s plan for response to rapidly 

and effectively manage oil spills that may result from drilling and production operations. ExxonMobil has 

designed its response program based on a regional capability of response to spills ranging from small 

operational spills to a worst discharge (WCD) from a well blowout. ExxonMobil’s spill response program 

meets the response planning requirements of the relevant coastal states and applicable Federal oil spill 

planning regulations and also includes information regarding ExxonMobil’s regional oil spill organization 

and dedicated response assets, potential spill risks, and local environmental sensitivities. The OSRP 

describes personnel and equipment mobilization, the incident management team organization, and an 

overview of actions and notifications to be taken in the event of a spill. All activities planned for WR 282 

are covered under this regional OSRP in accordance with 30 Code of Federal Regulations (CFR) Part 254. 

This EIA is organized into Sections A through I corresponding to the information required by 

NTL 2008-G04. The main impact-related discussions are in Section A (Impact-Producing Factors) and 

Section C (Impact Analysis). Table 1 lists and summarizes the NTLs applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact Analysis (EIA). 

NTL Title Summary 

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. 

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. 

2012-JOINT-G01 

Vessel Strike Avoidance and 

Injured/Dead Protected Species 

Reporting 

Recommends protected species identification guides be 

carried on all Gulf of Mexico petroleum vessels and that 

vessel operators and crews maintain a vigilant watch for 

marine mammals. Vessels are to slow down or stop to avoid 

striking protected species, and operators are required to 

report sightings of any injured or dead protected species. 

2011-JOINT-G01 

Revisions to the List of OCS Blocks 

Requiring Archaeological Resource 

Surveys and Reports 

Provides new information of which Outer Continental Shelf

(OCS) blocks require archaeological surveys and reports and 

required survey line spacing 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 scenario, and 

provides guidance regarding the information required in 

blowout scenario and worst case discharge scenario 

descriptions. 

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Table 1. (Continued). 

NTL Title Summary 

2009-G40 Deepwater Benthic Communities 

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 300 m 

(984 ft). Prescribes separation distances of 610 m (2,000 ft) 

from each mud and cuttings discharge location and 76 m 

(250 ft) from all other seafloor disturbances. 

2009-G39 Biologically Sensitive Underwater 

Features and Areas 

Guidance for avoiding and protecting biologically 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 300 m (984 ft) in the Gulf of Mexico. 

2009-G06 Military Warning and Water Test 

Areas 

Provides contact links to individual command headquarters 

for the military warning and water test areas in the Gulf of 

Mexico. Lease stipulations require lessees or designated 

operators to enter into an agreement with the appropriate 

individual military command headquarters concerning the 

control of electromagnetic emissions and use of boats and 

aircraft in the applicable warning area or water test area 

before commencing such traffic.

2008-G04 

Information Requirements for 

Exploration Plans and Development 

Operations Coordination 

Documents 

Guidance 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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A. Impact-Producing Factors 

Table 2 is a matrix of impact-producing factors (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 sections. 

• 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 

• Accidents 

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

The drilling rig proposed for this EP is the Transocean Deepwater Champion or a similar DP drillship. DP 

drillships use a global positioning system (GPS), specific computer software, and sensors in conjunction 

with their own propellers and thrusters to maintain position. Essentially, through satellite navigation, the 

location of the vessel is precisely monitored and thrusters positioned at various locations about the 

vessel’s hull are activated to provide any required station-keeping adjustment. This allows operations at 

sea where mooring or anchoring is not feasible. 

The drilling rig for the well proposed in this EP will be on site for an estimated 150 days. The physical 

presence of the drilling rig in the ocean can attract pelagic fishes and other marine life, as discussed in 

Section C.5.1. 

Drilling operations produce noise that includes strong tonal components at low frequencies, and in some 

cases infrasonic frequencies (MMS, 2000). According to Richardson et al. (1995), more sound is generally 

radiated underwater from drillships during drilling operations than from semisubmersibles, but this 

changes with the level of activity and age of equipment on the vessel. Drilling rigs also maintain exterior 

lighting for navigational and aviation safety in accordance with Federal regulations. This artificial lighting 

may attract and directly or indirectly impact natural resources. Flaring of gas from the rig may also attract 

and potentially impact natural resources, particularly birds. 

A.2 Physical Disturbance to the Seafloor 

Drillships like the Transocean Deepwater Champion do not use anchors for station-keeping or stabilization 

during drilling operations. The DP drillship will disturb only a very small area of the seafloor around the 

wellbore (SHL) where the bottom template and blowout preventer (BOP) are located. Depending on the 

specific well configuration, this area is generally about 0.25 ha (0.62 ac) (MMS, 2007a).

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Table 2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (--) 

Environmental Resources 

Impact-producing Factors

Drilling Rig 

Presence (incl. 

noise & lights) 

Physical 

Disturbance 

to Seafloor 

Air 

Pollutant 

Emissions 

Effluen

t Discharges

Water 

Intake 

Onshor

e Waste 

Disposal 

Mar

Debris 

Physical/Chemical Environment

Air quality and greenhouse gases -- -- --X(9) -- -- -- -Water quality -- -- -- X -- -- -

Seafloor Habitats and Biota

Soft bottom benthic communities -- X -- X -- -- -High-density deepwater benthic communities -- --(4) -- --(4) -- -- -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) -- -- -- -- -- -West Indian manatee (endangered) -- -- -- -- -- -- -Endangered mysticete whales -- -- -- -- -- -- -Non-endangered marine mammals (protected) X -- -- -- -- -- -Sea turtles (endangered/threatened) X(8) -- -- -- -- -- -Piping Plover (threatened) -- -- -- -- -- -- -Whooping Crane (endangered) -- -- -- -- -- -- -Gulf sturgeon (threatened) -- -- -- -- -- -- -Smalltooth sawfish (endangered) -- -- -- -- -- -- -Beach mice (endangered) -- -- -- -- -- -- -Elkhorn coral (endangered) -- -- -- -- -- -- -

Coastal and Marine Birds

Marine birds X -- -- -- -- -- -Shorebirds and coastal nesting birds -- -- -- -- -- -- -

Fisheries Resources

Pelagic communities and ichthyoplankton X -- -- X X -- -Essential Fish Habitat X -- -- X X -- -

Archaeological Resources

Shipwreck sites -- --(7) -- -- -- -- -Prehistoric archaeological sites -- --(7) -- -- -- -- -

Coastal Habitats and Protected Areas

Beaches -- -- -- -- -- -- -Wetlands and seagrass beds -- -- -- -- -- -- -Coastal wildlife refuges and wilderness areas -- -- -- -- -- -- -

Socioeconomic and Other Resources

Recreational and commercial fishing X -- -- -- -- -- -Public health and safety -- -- -- -- -- -- -Employment and infrastructure -- -- -- -- -- -- -Recreation and tourism -- -- -- -- -- -- -Land use -- -- -- -- -- -- -Other marine uses -- -- -- -- -- -- -

WCD = worst case discharge. 

Page 95 
Table 2 Footnotes and Applicability: 

(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any 

anchors will be on the seafloor within the following: 

(a) 4-mi zone of the Flower Garden Banks, or the 3-mi zone of Stetson Bank; 

(b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) protected by the Topographic 

Features Stipulation attached to an Outer Continental Shelf (OCS) lease; 

(c) Essential Fish Habitat (EFH) criteria of 500 ft from any no-activity zone; or 

(d) Proximity of any submarine bank (500-ft buffer zone) with relief greater than 2 m that is not protected by 

the Topographic Features Stipulation attached to an OCS lease. 

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or 

no-activity zone. There are no submarine banks in the block. 

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom 

(Pinnacle Trend) Stipulation attached to an OCS lease. 

• The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area. 

(3) Activities within any Eastern Gulf OCS block and portions of Pensacola and Destin Dome area blocks in the 

Central Planning Area where seafloor habitats are protected by the Live Bottom (Low-Relief) Stipulation 

attached to an OCS lease. 

• The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area. 

(4) Activities on blocks designated by the BOEM as being in water depths 300 m or greater. 

• No impacts on high-density deepwater benthic communities are anticipated. There are no features 

indicative of high-density chemosynthetic communities or coral communities within 610 m (2,000 ft) of 

the drilling mud/cuttings discharge location. 

(5) Exploration or production activities where H2S concentrations greater than 500 ppm might be encountered. 

• Based on 30 CFR 550.215, ExxonMobil is requesting that BOEM classify the lease area as “H2S absent.” 

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you 

determine would impact these environmental resources. If the proposed action is located a sufficient distance 

from a resource that no impact would occur, the EIA can note that in a sentence or two. 

• Accidental hydrocarbon spills could affect the resources marked (X) in the matrix, and impacts are 

analyzed in Section C. 

(7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated 

by the BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such 

blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the 

proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would 

occur, the EIA can note that in a sentence or two. 

• No impacts on archaeological resources are expected. The lease area is not on the list of archaeology 

survey blocks (BOEM, 2012c) and is well beyond the 60-m depth contour used by the BOEM as the 

seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. The geohazards and 

archaeological assessments indicate multiple sonar contacts in the lease area, but none are interpreted 

to be historic shipwrecks. A dynamic positioning drillship will be used; therefore, seafloor disturbances 

due to anchoring will not occur. 

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

or sea turtles or their critical habitats. 

• IPFs that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence, 

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. 

Page 96 Public Information Copy
A.3 Air Pollutant Emissions 

Air pollutant emissions are calculated in EP Section 8 and are estimated to be insignificant. Offshore air 

pollutant emissions will result from operations of the drillship, as well as service vessels and helicopters. 

These emissions occur from internal combustion engines, most of which are driven by diesel fuel. The 

combustion of fuels occurs on diesel-powered generators, pumps, or motors and from lighter fuel motors. 

Primary air pollutants typically associated with OCS activities are suspended particulate matter (PM), 

sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCs), and carbon monoxide (CO). 

The Air Quality Emissions Report prepared in accordance with BOEM requirements demonstrates that the 

projected emissions are below exemption levels set by the applicable regulations in 30 CFR 550.218. 

Based on calculated emissions and the well’s 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 are summarized in EP Appendix H. All offshore discharges will be in accordance with 

requirements of the National Pollutant Discharge Elimination System (NPDES) General Permit 

No. GMG290000 issued by the U.S. Environmental Protection Agency (USEPA). Any discharges will be in 

compliance with the permit terms and monitored as required by the permit. 

Water-based drilling muds and cuttings will be released at the seafloor during the initial well intervals 

before the marine riser that allows their return to the surface is set. Excess cement slurry will also be 

released at the seafloor during casing installation for the riserless portion of the drilling operations. 

Synthetic-based drilling muds (SBMs) will be collected on the rig and transported to the BHI facility in Port 

Fourchon, Louisiana, for processing and reuse. Cuttings wetted with SBMs will be discharged to the 

seafloor in accordance with the NPDES permit. 

Other effluent discharges in accordance with the NPDES permit will include excess cement, non-contact 

cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, 

uncontaminated freshwater and seawater, and ballast water. 

A.5 Water Intake 

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery on the 

drillship. 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 NPDES General Permit No. GMG290000 does not specify requirements for existing facilities 

(those that started construction before 16 July 2006). The DP drillship being considered for use in this EP 

is a “new” facility as defined by the NPDES permit and therefore triggers the cooling water intake 

regulations. The drillship will be in compliance with all cooling water intake requirements of the general 

NPDES permit. 

A.6 Onshore Waste Disposal 

Wastes generated during drilling are tabulated in EP Appendix H. A total of approximately 10 m3 (360 ft3) 

of trash will be generated over the life of this project. The trash will be transported in storage bins on a 

work boat to shore, where it will be moved by truck to the BFI Colonial landfill in Sorrento, Louisiana, and 

disposed of in accordance with applicable regulations. 

A.7 Marine Debris 

ExxonMobil will comply with all regulations relating to solid wastes handling and disposal, including the 

International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V 

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requirements and USEPA and U.S. Coast Guard (USCG) regulations, as well as those of the BOEM. For 

example, BOEM regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately 

discharging containers and other similar materials (i.e., trash and debris) into the marine environment, 

and 30 CFR 250.300(c) requires durable identification markings on equipment, tools, containers 

(especially drums), and other material. USEPA and USCG 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. In addition to the regulations in 30 CFR 250, 

BSEE issued 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. 

A.8 Support Vessel and Helicopter Traffic 

ExxonMobil will use existing shorebase facilities at Port Fourchon, Louisiana, for onshore support for vessel 

activities and air transportation (helicopters). The air onshore support base for helicopters will be located at 

the PHI heliport facility , and the marine onshore support base for the work and crew boats will be the CPort facility. These bases are capable of providing the services necessary for the proposed activities. No 

new facilities or workers will be needed for the proposed activities. 

The project will be supported by two crew boats and three offshore support vessels. The crew boats and 

offshore support vessels will each make approximately two round-trips per week. In addition, an 

installation supply vessel will make two trips per week to the project site. All boats typically will move to 

the project area via the most direct route from the shorebase. 

A helicopter will make one round-trip per day between the drillship and the heliport. The helicopter will 

be used to transport personnel and small supplies and will normally take the most direct route of travel 

between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters 

typically maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over 

unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats 

such as wildlife refuges and park properties. Additional guidelines and regulations specify that helicopters 

maintain an altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012d). 

Vessel noise is one of the main contributors to overall noise in the sea (National Research Council, 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, 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 

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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 

The analysis in this EIA focuses on two potential accidents: 

• a small fuel spill, which is the most likely type of spill during OCS exploration activities; and 

• the WCD for this EP, which is an oil spill resulting from an uncontrolled blowout. 

The following subsections summarize assumptions about the sizes and fates of these spills, as well as 

ExxonMobil’s spill response plans. Impacts are analyzed in Section C. 

MMS (2007b) and BOEM (2012b) analyzed three other types of accidents: chemical spills, vessel collisions, 

and loss of well control. These types of accidents are discussed briefly in Section A.9.4. 

A.9.2 Small Fuel Spill 

Spill Size. According to the analyses in MMS (2007b) and BOEM (2012a), the most likely type of small spill 

(<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have 

been ≤1 bbl, and this size is predicted to be the most common in ongoing and future OCS activities in the 

Western and Central Gulf of Mexico Planning Areas. As spill size increases, the incident rate declines 

dramatically (MMS, 2007b; BOEMRE, 2011a; 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, 2012a). 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 and response actions, it is expected that impacts from a 

small spill would be minimal (BOEMRE, 2011a; BOEM, 2012b). 

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic 

hydrocarbons (PAHs), which are moderately volatile (National Research Council, 2003b). The constituents 

of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic 

microbial oxidation. Because of its light density, diesel 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 (National Research Council, 2003b) 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 (National Oceanic and Atmospheric Administration [NOAA], 

2006). 

For purposes of this EIA, 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 over 90% of a small diesel spill would be 

evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it during this 24-

hour period would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and weather conditions. 

The ADIOS2 results coupled with spill trajectory information for a large spill discussed in Section A.9.3

indicate that a small fuel spill would not have any impacts on coastal or shoreline resources. The lease 

area is 261 km (162 miles) from the nearest shoreline. Modeling results discussed in Section A.9.3

indicate that a spill in the lease area would have a 4% or less probability of reaching the coastal areas of 

Page 99 Public Information Copy
Louisiana within 10 days after a spill. By that time, essentially 100% of a small fuel spill would have been 

dispersed or evaporated by natural processes, without taking into account ExxonMobil’s response 

measures. 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 (BOEM, 2012b). It is unlikely that a spill on the OCS would make landfall 

prior to dissipation because of the distance to shore and lack of persistence for such a spill (BOEM, 

2012b). 

Spill Response. In the unlikely event the shipboard prevention procedures fail to prevent a fuel spill, 

response equipment and trained personnel would be activated so that any spill effects would be localized 

and result only in short-term environmental consequences. EP Section 9 provides a detailed discussion of 

ExxonMobil’s response to a spill. 

A.9.3 Crude Oil Spill (Worst Case Discharge) 

Spill Size. In accordance with requirements of NTL 2010-N06, ExxonMobil has estimated a WCD for this EP 

as 175,895 barrels of oil per day. The detailed analysis of this calculation can be found in EP Section 2. 

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a 

probability of 0.0021 for a deep drilling blowout during exploration drilling based on U.S. Gulf of Mexico 

data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per 

exploratory well for non-North Sea locations (International Association of Oil & Gas Producers, 2010). As 

noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 

10% of blowouts resulted in spilled oil. BOEM is in the process of updating these spill frequency estimates 

to include the recent Macondo event; however, significant changes to the spill rates for the entire OCS are 

not anticipated (BOEMRE, 2011a; BOEM, 2012d). As noted in the Introduction, the baseline risk of a 

catastrophic blowout is estimated to be once every 26 years (BSEE Final Drilling Safety Rule, 75 FR 63365). 

Included in EP Section 2 are ExxonMobil’s calculations and information as required by NTL 2010-N06, 

including 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. ExxonMobil will also comply with 

NTL 2010-N10 and the Final Drilling Safety Rule, which specifies 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. Although this model 

has received some criticism recently (Earthjustice, 2011), it is still the most widely scientifically accepted 

model for estimating the fate of small fuel spills. The primary criticism of the OSRA model results as 

provided in Ji et al. (2004) was that the model did not evaluate the fate of a spill over time periods longer 

than 30 days, nor did it predict the fate of a release that continues over a period of weeks or months, as in 

the Macondo incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the 

chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill 

response activities. The model does not assume a particular spill size but has generally been used by the 

BOEM to evaluate contact probabilities for spills greater than 1,000 bbl. 

To address this criticism, a special OSRA run was conducted for the recent BOEM Western and Central 

Gulf of Mexico Planning Area Supplemental EISs (BOEMRE, 2011a; BOEM, 2012b) in order to estimate the 

impacts of a possible future catastrophic long-duration oil spill. In this OSRA model run, a hypothetical 

high volume, long-duration oil spill was assumed to have occurred, and the analysis emphasized modeling 

a spill that continued for 90 consecutive days, with each trajectory tracked for up to 120 days. 

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The OSRA model run for this revised analysis was conducted for five hypothetical launch points in the 

Central and Western Gulf of Mexico Planning Areas. These launch points were deliberately located in 

areas identified as having a high possibility of containing large oil reserves. 

The five launch point areas were as follows: 

1. Central Gulf of Mexico shelf area west of the Mississippi River (28.98660° N latitude, 92.17851° W 

longitude); 

2. Central Gulf of Mexico shelf area east of the Mississippi River (29.91388° N latitude, 88.15338° W 

longitude); 

3. Central Gulf of Mexico slope area (27.31998° N latitude, 90.22203° W longitude); 

4. Western Gulf of Mexico shelf area (27.55423° N latitude, 96.76627° W longitude); and 

5. Western Gulf of Mexico slope area (27.51367° N latitude, 94.51836° W longitude). 

The results for Launch Point 3, the launch point nearest to the project area, are presented in Table 3.

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Table 3. Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 3 

will contact a certain parish, county, or coastline within 120 days (Modified from: BOEM, 

2012b, Appendix C). 

Season Winter Spring Summer Fall 

Day 0 0 20 0 0 20 0 0 20 0 0 20

County or Parish, 

State Percent Chance 

Cameron, Texas 

- - - - - - - - - - - - - 

Willacy, Texas 

- - - - - - - - - - - - -

Kenedy, Texas 

- - - - - - - - - - - -

Kleberg, Texas 

- - - - - - - - - - - 

Nueces, Texas 

- - - - - - - - - - - 

Aransas, Texas 

- - - - - - - - - - - -

Calhoun, Texas 

- - - - - - - - - - -

Matagorda, Texas - - 7 - - - - - 1 - - 

Brazoria, Texas - - 2 - - - - - - 

Galveston, Texas 

- - 0 - - - - - -

Jefferson, Texas 

- - - - - - - - - 

Cameron, 

Louisiana - - - - 1 2 - - - - 

Vermilion, 

Louisiana - - - - - - - - -

Iberia, Louisiana 

- - - - - - - - - - - - -

Terrebonne, 

Louisiana - - 2 4 - - - - - - - 

Lafourche, 

Louisiana - - - 0 - - - - - - 

Jefferson,

Louisiana - - - - - - - - - - -

Plaquemines, 

Louisiana - - - - 0 2 - - - - - -

Jackson, 

Mississippi - - - - - - - - - - - - - - 

Baldwin, Alabama 

- - - - - - - - - - - - - - 

Bay, Florida 

- - - - - - - - - - - - - - -

Franklin, Florida 

- - - - - - - - - - - - - - - 

Monroe, Florida 

- - - - - - - - - - - - - - 

Dade, Florida 

- - - - - - - - - - - - - - -

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"—" = Values <1.0%. Areas where there is <0.5% chance of contact within 120 days are not shown. 

OSRA is a preliminary risk assessment model. In the event of an actual oil spill, real-time monitoring and 

trajectory modeling would be conducted using current and wind data available from the rigs and 

permanent production structures in the area. Satellite and aerial monitoring of the plume and real-time 

trajectory modeling using wind and current data would continue on a daily basis to help position 

equipment and human resources throughout the duration of any major spill or uncontrolled release. 

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, influencing potential 

effects to 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 particulate matter, 

and stranding on shore or sedimentation to the seafloor (National Research Council, 2003b). 

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 a slick on the water surface. Evaporated hydrocarbons are degraded 

rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine 

bacteria removes first the n-alkanes and then the light aromatics from the oil. Other petroleum 

components are biodegraded more slowly. Photo-oxidation attacks mainly the medium and high 

molecular weight PAHs in the oil on the water surface. 

Spill Response. BOEM has issued recent NTLs following the Macondo spill that clarify additional oil spill 

prevention and response planning requirements. These NTLs are summarized in Table 2, and additional 

BOEM (2012b) guidance is provided below. 

NTL 2012-N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the Coast Line 

Concerning Regional Oil Spill Response Plans: This NTL, effective 10 August 2012, provides 

clarification, guidance, and information on the preparation and submittal of regional OSRPs for 

owners and operators of oil handling, storage, or transportation facilities, inclusive of pipelines, 

located seaward of the coastline. It states that lessees, designated operators, and pipeline right-ofway holders are responsible for preparation and submission of these plans. Some of the clarifications 

and recommended practices in the NTL are based on lessons learned from the Macondo oil spill 

response.

NTL 2010-N10 – Statement of Compliance with Applicable Regulations and Evaluation of Information 

Demonstrating Adequate Spill Response and Well Containment Resources: 

This NTL, effective 8 November 2010, applies only to operators conducting operations using subsea or 

surface BOPs on floating facilities. It requires that lessees and operators must submit a statement 

signed by an authorized company official with each well permit application indicating that they will 

conduct all of their authorized activities in compliance with all applicable regulations, including the 

Increased Safety Measures Regulations at 75 FR 63346. The NTL also informs lessees that BOEMRE 

will evaluate whether the operator has submitted adequate information demonstrating that it has 

access to and can deploy surface and subsea containment resources that would be adequate to 

promptly respond to a blowout or other loss of well control. The NTL notifies the operator that 

BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current 

OSRP; therefore, there is an incentive for voluntary compliance. 

NTL 2010-N06 – Information Requirements for Exploration Plans, Development and Production Plans, 

and Development Operations Coordination Documents on the OCS: 

This NTL, effective 18 June 2010, explains the procedures for the lessee or operator to submit 

supplemental information for new or previously submitted EPs, Development and Production Plans, 

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or Development Operations Coordination Documents. The required supplemental information 

includes the following: (1) a description of the blowout scenario as required by 30 CFR 254(b) and 

254(h); (2) a description of their assumptions and calculations used in determining the volume of the 

WCD required by 30 CFR 254.26; and (3) a description of the measures proposed that would enhance 

the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and 

early intervention in the event of a blowout, including the arrangements for drilling relief wells and 

any other measures proposed. The early intervention methods of the third requirement could 

actually include the surface and subsea containment resources that BOEM announced in NTL 2010-

N10, which states that BOEM will review to ensure that the measures are adequate to promptly 

respond to a blowout or other loss of well control. 

• ExxonMobil submitted an updated Gulf of Mexico Regional OSRP to BOEM in December 2010 

and July and December 2011; the ORSP is pending approval. The OSRP provides a detailed plan for 

ExxonMobil to respond rapidly to and effectively manage oil spills that may result from drilling and 

production operations. 

In the event of a WCD, ExxonMobil has access to surface and subsea response/containment capabilities 

that could be implemented through various organizations under contract. ExxonMobil's primary spill 

response equipment provider is Clean Gulf Associates (CGA). 

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore areas. 

These vessels have oleophilic brush pack skimming systems operating in troughs built into the hulls, 

below-deck storage, and marine electronics packages including marine, aircraft and company-frequency 

radios; radar; moving map plotters; GPS; satellite phones; and depth finders. CGA also offers nine Fast 

Response Systems staged throughout the Gulf of Mexico that are available for offshore use. 

The CGA high-volume open sea skimmer (HOSS) barge consists of a skimming system built into an oil 

recovery barge. There are four 1,000-bbl recovered oil storage tanks built into the hull where oil can be 

separated and offloaded. Skimming operations are conducted from the control room overlooking the 

skimmer deck. The estimated daily recovery capacity for the HOSS barge is approximately 43,000 bbl. 

CGA is currently adding to its equipment stockpile and has acquired 11 sets of Koseq skimming arms and 

two Aqua Guard skimmers. In addition, an x-band radar/infrared tracking system is installed on the HOSS 

barge. Additional CGA equipment can be referenced on their website: http://www.cleangulfassoc.com/. 

ExxonMobil also has a contract with the Marine Spill Response Corporation (MSRC) for additional spill 

response equipment. MSRC has a dedicated fleet for the Atlantic/Gulf of Mexico region and additional 

available equipment staged throughout the U.S. MSRC equipment staged throughout the Gulf of Mexico 

includes seven oil spill response vessels, two fast response vessels, five oil spill response barges, five 

platform supply vessels, and 15 shallow water barges. Various equipment is outfitted with x-band and 

infrared technology. 

MSRC recently completed a large expansion of its resources and capabilities in the Gulf of Mexico, with 

particular focus on deepwater. Additional information on MSRC capabilities and a complete equipment 

listing are available on-line at http://www.msrc.org/. 

See EP Section 9 for a detailed description of ExxonMobil’s site-specific response to the WCD for this plan. 

A.9.4 Other Accidents Not Analyzed in Detail 

BOEM (2012b) discusses three other types of accidents: chemical spills, vessel collisions, and loss of well 

control. The information from the EIS on these topics remains valid and is incorporated by reference into 

this document. These accidents are discussed briefly below along with a hydrogen sulfide (H2S) release. 

There are no other site-specific issues for the drilling of the well proposed in this EP. 

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Chemical Spills. Chemicals are stored and used to condition drill muds and during production and in well 

completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the 

largest volumes spilled. Completion fluids are the largest quantity used and comprise the largest releases. 

Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The 

most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production 

chemicals are needed in deepwater operations where gas hydrates tend to form. Spill volumes are 

anticipated to remain about the same, but spill frequency can be expected to decrease because of 

advances in subsea processing (BOEMRE, 2011a; BOEM, 2012b). 

Riser Disconnect SBM Spills. In deepwater drilling, SBMs are preferred over petroleum oil-based muds 

(OBMs) due to the superior environmental properties of SBMs. The synthetic base fluids used in SBMs are 

less toxic to the marine environment and have the potential to biodegrade. SBMs have been used in the 

Gulf of Mexico since the mid-1990s, and between 5 and 20 SBM releases are anticipated each year as a 

result of offshore drilling programs. The majority of these releases are <50 bbl in size, but accidental riser 

disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,381 bbl) quantities of 

drilling fluids. Riser disconnect accidents are of particular concern when SBMs are in use (BOEMRE, 

2011b). 

Vessel Collisions. BOEM data show that from 1996 to 2009 there were 226 OCS-related collisions. Most 

collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline 

risers. Approximately 10% of vessel collisions with platforms in the OCS resulted in diesel spills, and in 

several collision incidents, fires resulted from hydrocarbon releases. To date, the largest diesel spill 

associated with a collision occurred in 1979 when an anchor-handling boat collided with a drilling 

platform in the Main Pass lease area, spilling 1,500 bbl. Diesel fuel is the product most frequently spilled, 

but oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result 

of vessel collisions. Human error accounted for approximately half of all reported vessel collisions from 

2006 to 2009. As summarized in MMS (2007b) and BOEM (2012b), vessel collisions occasionally occur 

during routine operations. Some of these collisions have caused spills of diesel fuel or chemicals. 

ExxonMobil will comply with all 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 very minor up to the most serious well control incidents, while blowouts are considered to be a 

subset of more serious incidents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well 

control may result in the release of synthetic drilling fluid or loss of oil. ExxonMobil has a robust system in 

place to prevent loss of well control. Measures to prevent a blowout, reduce the likelihood of a blowout, 

and conduct effective and early intervention in the event of a blowout are described in the NTL 2010-06 

package submitted with the EP, as required. The potential for a loss-of-well-control event will be 

minimized by adhering to the requirements of applicable regulations such as the Final Drilling Safety Rule 

and NTL 2010-N10, which specify additional safety measures for OCS activities. 

H2S Release. Pursuant to 30 CFR 550.215, ExxonMobil is requesting in the EP that the BOEM Regional 

Supervisor, Field Operations, classify the area in the proposed drilling operations as H2S absent. 

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B. Affected Environment 

The lease area is in the central Gulf of Mexico, 261 km (162 miles) from the nearest shoreline, and 287 km 

(178 miles) from the onshore support base at Port Fourchon, Louisiana (Figure 1). 

Based on the geohazard assessment conducted by Gardline Surveys Inc. (2010), water depth at the 

wellsite is anticipated to be 1,937 m (6,354 ft) (Figure 2). There are no seafloor faults, mounds, 

depressions, or other significant seafloor features at the proposed well location. There is no evidence of 

fluid expulsion features, or high-density deepwater benthic communities near the proposed wellsite 

(Gardline Surveys Inc., 2010). A detailed description of the regional affected environment, 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 is provided in lease sale EISs (MMS, 2007b; BOEM, 2012b). These regional 

descriptions remain valid and are incorporated by reference. General background information is 

presented below, and brief descriptions of each potentially affected resource, including site-specific 

and/or new information if available, are presented in Section C. 

The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the oil slick 

on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants were 

applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). Despite 

limited information on the water quality of deep water, it is clear that conditions in the offshore waters of 

the Gulf of Mexico were altered by the Macondo event. Various monitoring efforts and environmental 

studies are in progress, but it is not currently possible to precisely estimate the long-term impacts the spill 

will have on offshore water quality (BOEMRE, 2011a; BOEM, 2012a). 

The lease area is located approximately 348 km (216 miles) southwest of the Macondo spill site. Based on 

an analysis of satellite imagery, the surface slick did not extend over the lease area, and the existing water 

quality in the lease area is not expected to have been affected by the Macondo release. Prior to the 

Macondo incident, water quality in deep, offshore waters of the Gulf of Mexico was expected to be good, 

with low levels of contaminants (Kennicutt, 2000). Based on the information currently available, there is 

no reason to expect any long-term change in water quality conditions in the lease area from those 

predicted in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and the Programmatic EIS (BOEM, 2012d). 

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Figure 2. Bathymetric map of the lease area showing the surface hole location of Well "A" in Walker Ridge Bloc

Page 107 
C. Impact Analysis 

This section analyzes the potential direct and indirect impacts of routine activities and accidents. Impacts 

have been analyzed extensively in multi-lease-sale EISs for the Western and Central Gulf of Mexico 

Planning Areas (MMS, 2007b; BOEM, 2012b). The information in these documents is incorporated by 

reference. Potential site-specific issues are addressed in this section. 

C.1 Physical/Chemical Environment 

C.1.1 Air Quality 

There are no site-specific air quality data for the project area due to the distance from shore. Because of 

the distance from shore-based pollution sources and the lack of sources offshore, air quality at the 

wellsite is expected to be good. The attainment status of Federal OCS waters is unclassified because 

there is no provision in the Clean Air Act for classification of areas outside State waters (MMS, 2007b). 

As noted earlier, based on calculations made pursuant to applicable regulations, emissions from drilling 

activities are not expected to be significant as they are below exemption levels. Therefore, the only 

potential effects to air quality would be from routine air pollutant emissions, a small fuel spill, and a large 

oil spill (WCD). 

BOEM has reexamined the analysis for air quality presented in MMS (2007b, 2008) based on additional 

information and in consideration of the Macondo oil spill event. No substantial new information was 

found that would alter the potential impacts on air quality presented in previous lease sale EISs (BOEMRE, 

2011a; BOEM, 2012b). 

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 drillship operations and helicopters and service vessels. These emissions occur mainly 

from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel-powered 

generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated 

with OCS activities are suspended PM, SOx, NOx, VOCs, and CO. Emissions of pollutants into the 

atmosphere from these 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 described in recent lease sale EISs, the incremental contribution to cumulative impacts 

from activities similar to ExxonMobil’s proposed activities is not significant and will not cause or 

contribute to a violation of any National Ambient Air Quality Standard (NAAQS) (MMS, 2007b, 2008). 

Since the BOEM completed the lease sale EISs, the USEPA has adopted a new short-term NAAQS for 

nitrogen dioxide (NO2). The standard has not yet been implemented in the Gulf Coast states, but given 

the levels of expected emissions and the distance of the project from shore, emissions from the activities 

described in ExxonMobil’s proposed EP are not likely to contribute to violations of any NAAQS onshore. 

Carbon dioxide (CO2) and methane (CH4) emissions from the project would constitute a small incremental 

contribution to greenhouse gas emissions from all OCS activities. According to recent programmatic and 

OCS lease sale EISs (BOEM, 2012a,d), estimated CO2 emissions from OCS oil and gas sources are 0.4% of 

the U.S. total. All OCS activities contribute approximately 0.005% to total global CO2 emissions. 

Greenhouse gas emissions may contribute to climate change, with important effects on temperature, 

rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on 

Climate Change, 2007). Greenhouse gas emissions from this 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, 2012d). 

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Because of the distance from shore, routine operations in the project area are not expected to have any 

impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale 

EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central Gulf of Mexico 

Planning Area are projected to have minimal impacts to onshore air quality because of the prevailing 

atmospheric conditions, emission heights, emission rates, and the distance of these emissions from the 

coastline. The Air Quality Emissions Report (see EP Section 8 and Appendix F) prepared in accordance 

with BOEM requirements shows that the projected emissions are below exemption levels; therefore, 

according to 30 CFR 250.303, the emissions will not significantly affect the air quality of the onshore area 

for any of the criteria pollutants. No further analysis or control measures are required. 

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 Class I air quality area. The BOEM is 

required to notify the National Park Service and U.S. Fish and Wildlife Service (USFWS) if emissions from 

proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be 

required for sources within 186 miles (300 km) of the Breton Class I area that exceed emission limits 

agreed upon by the administering agencies (National Park Service, 2010). The lease area is approximately 

358 km (222 miles) from the Breton Wilderness Area, and no air quality impacts on the Wilderness Area 

are expected. ExxonMobil will comply with all BOEM requirements regarding air emissions. 

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 EISs prepared for lease sales (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS 

(BOEM, 2012d). The probability of a small spill would be minimized by ExxonMobil’s preventative 

measures during routine operations, including fuel transfer. In the unlikely event of a spill, 

implementation of ExxonMobil’s OSRP will reduce the potential impacts. EP Section 9 includes a detailed 

discussion of the spill response measures that would be employed. Given the open ocean location of the 

lease area, the extent and duration of air quality impacts from a small spill would not be significant. 

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The 

ADIOS2 model (see Section A.9.2) indicates that over 90% of a small diesel spill would be evaporated or 

dispersed within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions. 

A small fuel spill would not affect coastal air 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 (WCD) 

Potential impacts of a large oil spill on air quality are expected to be consistent with those analyzed and 

discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 

2012d). 

A large oil spill (WCD) could potentially 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. Real-time wind and current data 

from the project area would be available at the time of a spill and would be used to assess the fate and 

effects of VOCs released. Additional air quality impacts could occur if response measures included in situ

burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of 

NOx, SOx, CO, and PM, as well as greenhouse gases. However, in situ burning would occur only after 

authorization from the USEPA. 

Because of the lease area location (261 km [162 miles] from the nearest shoreline), most air quality 

impacts would occur in offshore waters with minimal chance to affect onshore air quality. 

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C.1.2 Water Quality 

There are no site-specific water quality data for the lease area. Because the lease location is in deep, 

offshore waters, water quality is expected to be good, with low levels of contaminants. As noted in a 

lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively homogeneous 

with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has 

little evidence of contaminants in the dissolved or particulate phases of the water column. However, 

there are localized occurrences of natural seepage of oil, gas, and brines in near-surface sediments and up 

through the water column. 

The lease area is located approximately 348 km (216 miles) from the Macondo spill site. Based on the 

general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface slick from that 

discharge did not extend over the lease area during the spill, and the existing water quality in the lease 

area is not expected to have been affected by the Macondo release. 

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

and a large oil spill (WCD). 

Impacts of Effluent Discharges 

In general, turbid water can be expected to extend between a few hundred meters and several kilometers 

down current from the discharge point for water-based drilling muds and cuttings. SBMs will be collected 

on the rig and either reused by the vendor or transported to Port Fourchon for recycling and/or disposal 

in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with 

the NPDES permit. All NPDES permit limitations and requirements will be met. There will be no 

persistent impacts on water quality in the lease area (National Research Council, 1983; Neff, 1987; Neff et 

al., 2000). 

Treated sanitary and domestic wastes, including those from support vessels, may have a slight transient 

effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and 

requirements and USCG regulations (as applicable) will be met, therefore, little or no impact on water 

quality is anticipated. 

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, 

and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling 

rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other 

areas such as chemical storage areas and places where equipment is exposed will be collected and oil and 

water separated to meet NPDES permit requirements. Based on adherence to permit limits and 

applicable regulations, little or no impact on water quality is anticipated. 

Other discharges in accordance with the NPDES permit, such as desalination unit brine and 

uncontaminated cooling water, fire water, and ballast water, are expected to be diluted rapidly, resulting 

in little or no impact 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 lease sale EISs (MMS, 2007b; BOEM, 2012a,b). The probability of a small spill would be 

minimized by ExxonMobil’s preventative measures during routine operations, including fuel transfer. In 

the unlikely event of a spill, implementation of ExxonMobil’s OSRP will potentially help mitigate and 

reduce the impacts. EP Section 9 provides detail on spill response measures in addition to the summary 

information provided in this EIA. 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. 

Page 110 Public Information Copy
A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of 

impacts would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. However, it is estimated that over 90% of a small diesel spill 

would be evaporated or dispersed within 24 hours (see Section A.9.2). The area of the sea surface with 

diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), 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 (National Research Council, 2003b). The constituents of these oils are light to intermediate in 

molecular weight and can be readily degraded by aerobic microbial oxidation. Because the density of 

diesel is less than the density of seawater, diesel 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 (National Research Council, 2003b) and would not be expected to occur 

to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely 

degraded by naturally occurring microbes (NOAA, 2006). 

A small fuel spill would not affect coastal water quality because the spill would not be expected to make 

landfall or reach coastal waters due to both response efforts that would be undertaken as well as natural 

attenuation (see Section A.9.2). 

Impacts of a Large Oil Spill (WCD) 

Potential impacts of a large oil spill on water quality are expected to be consistent with those analyzed 

and discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the current Programmatic EIS (BOEM, 

2012d). A large spill would affect water quality by producing a slick on the water surface and increasing 

the concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at the time 

and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the 

surface, although new information from the Macondo spill indicates that plumes of submerged oil 

droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen 

et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval 

from the USEPA. Small droplets in the water may adhere to suspended sediments and be removed from 

the water column (Operational Scientific Advisory Team, 2010). 

Because of the lease area location (261 km [162 miles] from the nearest shoreline), it is expected that 

most water quality impacts would occur in offshore waters, especially in the event of a spill lasting less 

than 30 days (Table 3). 

C.2 Seafloor Habitats and Biota 

Water depth at the proposed project area is approximately 1,937 m (6,354 ft). There are no seafloor 

faults, mounds, depressions, or other significant seafloor features at the proposed well location. No areas 

of possible hard bottom or microseepages were seen within 610 m (2,000 ft) of the wellsite (Gardline 

Surveys Inc., 2010). 

Based on the absence of hard bottom areas detected by side-scan sonar during the site clearance survey, 

the seafloor within 610 m (2,000 ft) of the wellsite is expected to consist mainly of soft bottom 

communities. The geohazard assessment did not identify any features that could support high-density 

deepwater benthic communities within 610 m (2,000 ft) of the wellsite. No areas of gaseous sediments or 

possible hydrocarbon seepage were defined within 610 m (2,000 ft) of the wellsite, and the presence of 

chemosynthetic communities is considered negligible (Gardline Surveys Inc., 2010).

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C.2.1 Soft Bottom Benthic Communities 

There are no site-specific benthic community data from the lease area. However, 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 collected 

at stations in water depths similar to the proposed drilling area. 

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 

(Adapted from: Wei, 2006; Rowe and Kennicutt, 2009). 

Statio

n 

Water 

Depth 

(m) 

Abundance 

Meiofauna

(individuals/m2) 

Macroinfauna

(individuals/m2) 

Megafauna

(individuals/ha) 

NB5 2,063 117,263 706 1,600 

NB3 1,875 165,245 1,342 191 

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal abundance from 

Wei (2006). 

Densities of meiofauna (animals passing through a 0.5-mm sieve but retained on a 0.062-mm sieve) in 

water depths representative of the lease area (1,937 m [6,354 ft]) typically range from approximately 

120,000 to 290,000 individuals/m2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid 

copepods were the three dominant meiofaunal groups, accounting for about 90% of total abundance. 

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which 

reflect the meager primary production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease 

exponentially with water depth. Based on an equation presented by Wei (2006), macroinfaunal densities 

in the water depths of the lease area are expected to be about 1,620 individuals/m2. 

Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of Mexico 

continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four 

depth-dependent faunal zones (1 through 4), two of which are divided horizontally. The lease area is in 

Zone 3W, which includes the Alaminos Canyon (basin and non-basin sites) as well as the base of the 

Sigsbee Escarpment, with stations ranging in depth from 6,152 to 9,869 ft (1,875 to 3,008 m). The most 

abundant species in Zone 3W were the polychaetes Levinsenia uncinata, Paraonella monilaris, and 

Tachytrypane sp. A; the bivalve Heterodonta sp. B; and the isopod Macrostylis 256. Megafaunal densities 

from nearby stations ranged from 191 to 1,600 individuals/ha (Table 4). Common megafauna included 

motile groups such as decapods, ophiuroids, holothurians, and demersal fishes, as well as sessile groups 

such as sponges and anemones. 

Bacteria also 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 about 1 to 2 g C/m2 in the top 

15 cm of sediments (Rowe and Kennicutt, 2009). 

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent 

discharges (drilling muds and cuttings), and a large oil spill (WCD) 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 

In water depths such as are encountered in the lease area, DP drillships disturb the seafloor only around 

the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well 

configuration, this area is generally about 0.25 ha (0.62 ac). 

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The areal extent of these impacts from the DP drillship will be small compared to the lease area itself, and 

these types of 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 the physical 

disturbance of the seafloor during this project will have no significant impact on soft bottom benthic 

communities in the region. 

Impacts of Effluent Discharges 

Drilling muds and cuttings are the only effluents that are likely to affect benthic communities. During 

initial well interval(s) before the marine riser is set, cuttings and seawater-based "spud mud" will be 

released at the seafloor. Excess cement slurry will also be released at the seafloor during casing 

installation for the riserless portion of the drilling operations. Cement slurry components typically include 

cement mix and some of the same chemicals used in water-based drilling muds (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 muds, and cement slurry will 

eventually be recolonized through larval settlement and migration from adjacent areas. Because some 

deep-sea biota grow and reproduce slowly, recovery may require several years. 

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily within several 

hundred meters of the wellsite. 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, washed cuttings with adhering SBMs tend to clump together and 

form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated 

organic carbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where 

SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, 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. Assuming a typical effect radius of 

500 m (1,640 ft), the affected area around the wellsite would represent about 3% of the seafloor within a 

lease block. 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 in the region. 

Impacts of a Large Oil Spill (WCD) 

The most likely effects of a subsea blowout on benthic communities would be within a few hundred 

meters of the wellsite. The MMS (2007b) estimated that a severe subsurface blowout could resuspend 

and disperse sediments within a 300-m (984-ft) radius. While coarse sediments (sands) would probably 

settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) could 

be resuspended for more than 30 days and dispersed over a much wider area. Based on previous studies, 

surface sediments at the project area are assumed to largely be silt and clay (Rowe and Kennicutt, 2009). 

Page 113 Public Information Copy
Previous lease sale EISs (MMS, 2007a, 2008) indicated that oil spills would be unlikely to affect benthic 

communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) 

because the oil would rise quickly to the sea surface directly over the spill location. However, during the 

Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending 

at least 22 miles (35 km) from the wellsite and persisting for more than a month (Camilli et al., 2010). The 

subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 

2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume 

could contact the seafloor and affect benthic communities beyond the 300-m (984-ft) radius estimated by 

MMS (2007a, 2008), depending on its extent, trajectory, and persistence. This contact could result in 

smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic 

organisms over a period of months to years (National Research Council, 2003b). 

C.2.2 High-Density Deepwater Benthic Communities 

As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas that 

could support high-density chemosynthetic communities, or features or areas that could support highdensity deepwater corals and other associated high-density hard bottom communities. Chemosynthetic 

communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively 

(MacDonald, 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. 

The nearest known chemosynthetic community site is approximately 111 km (69 miles) north-northeast 

of the lease area in Green Canyon Block 287. The nearest identified deepwater coral communities are in 

Green Canyon Block 852, 49 km (30 miles) north-northwest of the lease area. 

The geohazard assessment of the lease area did not identify any features that could support high-density 

deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling mud/cuttings discharge 

locations (Gardline Surveys Inc., 2010). 

IPFs potentially affecting high-density deepwater benthic communities include physical disturbance of the 

seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at 

the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float 

and dissipate on the sea surface. 

Impacts of Physical Disturbance to the Seafloor 

In water depths such as are encountered in the lease area, DP drillships disturb the seafloor only around 

the wellbore (SHL) where the bottom template and BOP are located. Depending upon the specific well 

configuration, this area is generally about 0.25 ha (0.62 ac). 

The areal extent of these impacts from the DP drillship will be small, and NTL 2009-G40 requires that 

high-density deepwater benthic communities and features or areas that could support high-density 

chemosynthetic communities or deepwater coral communities be avoided. Based on the information 

presented in Gardline Surveys Inc. (2010), there will be no impacts on chemosynthetic or deepwater coral 

communities from this project. 

Impacts of Effluent Discharges 

The geohazard assessment (Gardline Surveys Inc., 2010) did not identify any features that could support 

high-density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling locations, 

and the presence of chemosynthetic communities in the lease area is considered negligible. Monitoring 

programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling 

discharges typically are concentrated within about 500 m (1,640 ft) of the wellsite, although detectable 

deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 

Page 114 Public Information Copy
2005). Because of the water depth of the lease area, drilling discharges would be expected to result in 

thinner, more diffuse accumulations on the seafloor than those documented in the literature. Although 

small amounts of cuttings particles may reach areas inhabited by high-density deepwater benthic 

communities, the discharges are not expected to result in significant impacts to these communities. 

Impacts of a Large Oil Spill (WCD) 

The current Programmatic EIS (BOEM, 2012d) concluded that oil spills would be unlikely to affect benthic 

communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) 

because the oil would rise quickly to the sea surface directly over the spill location. However, during the 

Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending 

at least 35 km (22 miles) from the wellsite and persisting for more than a month (Camilli et al., 2010). The 

subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 

2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume 

could have the potential to contact high-density deepwater benthic communities beyond the 300-m 

(984-ft) radius estimated by BOEM (2012d), depending on its extent, trajectory, and persistence. Oil 

plumes that contact sensitive benthic communities before degrading could potentially impact the 

resource (BOEM, 2012b). Potential impacts on sensitive resources would be an integral part of the 

decision and approval process for the use of dispersants, and such approval would be obtained from the 

USEPA prior to the use of dispersants. 

The biological effects and expected fate of the oil remaining in the Gulf of Mexico from the Macondo 

blowout are still unknown due to the depth and the magnitude of this event. Hazen et al. (2010) reported 

changes in plume hydrocarbon composition with distance from the source. Incubation experiments with 

environmental isolates demonstrated faster-than-expected hydrocarbon biodegradation rates at 5°C. 

Based on these results, Hazen et al. (2010) suggested the potential exists for intrinsic bioremediation of 

the oil plume in the deep water column without substantial oxygen drawdown. 

Potential impacts of oil on high-density deepwater benthic communities are discussed in MMS (2007b). 

Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very constant 

and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep 

organisms also 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, 2012d). 

The potential for a spill to affect deepwater corals is indicated by preliminary findings from an 

October 2010 survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). 

Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 

11 km (7 miles) southwest of the Macondo wellhead when they observed dead and dying corals with 

sloughing tissue and discoloration. Much of the soft coral observed in an area measuring about 15 by 

40 m (50 by 130 ft) was covered by what appeared to be a brown flocculent substance (floc). Out of 40 

large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 

400 m (1,312 ft) farther away had a colony of stony corals similarly affected and partially covered with a 

similar brown substance. Based on hopanoid petroleum biomarkers from the floc, researchers concluded 

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; corals elsewhere in the Gulf of Mexico 

outside the area affected by the plume did not appear to be experiencing higher mortality. The research 

team concluded that the observed coral injuries likely resulted from exposure to the subsurface oil plume 

(White et al., 2012). 

Page 115 Public Information Copy
C.2.3 Designated Topographic Features 

The block is not within or near a designated topographic feature or a no-activity zone as identified in NTL 

2009-G39. The nearest designated topographic feature is Jakkula Bank in Green Canyon Block 50, 147 km 

(91 miles) north-northwest of the lease area. 

There are no IPFs associated with either routine operations or accidents that could cause impacts to 

designated topographic features because of their distance from the lease area. A small fuel spill would 

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. 

If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and 

the difference in water depth. Near-bottom currents in the region are predicted to flow along the 

isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge. 

C.2.4 Pinnacle Trend Area Live Bottoms 

The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by 

NTL 2009-G39, the nearest pinnacles stipulation block is Main Pass Block 290, 382 km (237 miles) 

northeast of the lease area. 

There are no IPFs associated with either routine operations or accidents that could cause impacts to 

pinnacle trend area live bottoms due to the distance from the lease area. A small fuel spill would float on 

the surface and would not reach these seafloor features. 

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. 

If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and 

the difference in water depth. Near-bottom currents in the region are predicted to flow along the 

isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge. 

C.2.5 Eastern Gulf Live Bottoms 

The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which pertains to seagrass 

communities and low-relief hard bottom reef within the Eastern Gulf of Mexico Planning Area blocks in 

water depths of 100 m (328 ft) or less and portions of Pensacola and Destin Dome Area blocks in the 

Central Gulf of Mexico Planning Area. The nearest block covered by the live bottom stipulation, as 

defined by NTL 2009-G39, is Destin Dome Block 573, approximately 443 km (275 miles) northeast of the 

lease area. 

There are no IPFs associated with either routine operations or accidents that could cause impacts to 

eastern Gulf live bottom areas because of the distance from the lease area. A small fuel spill would float 

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. 

If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and 

the difference in water depth. Near-bottom currents in the region are predicted to flow along the 

isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf. 

C.3 Threatened, Endangered, and Protected Species and Critical Habitat 

This section discusses species listed as endangered or threatened under the Endangered Species Act 

(ESA). In addition, it includes all marine mammal species in the region, which are protected under the 

Marine Mammal Protection Act (MMPA). 

Endangered or threatened species that may occur in the project area and/or along the northern Gulf 

Coast are listed in Table 5. The table also indicates the location of critical habitat (if designated in the Gulf 

Page 116 Public Information Copy
of Mexico). Critical habitat is defined as (1) specific areas within the geographical area occupied by the 

species at the time of listing, if they contain physical or biological features essential to conservation, and 

those features may require special management considerations or protection; and (2) specific areas 

outside the geographical area occupied by the species if the agency determines that the area itself is 

essential for conservation. The National Marine Fisheries Service (NMFS) has jurisdiction for ESA-listed 

cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for ESA-listed birds 

and the West Indian manatee. 

Table 5. Federally listed endangered and threatened species potentially occurring in the lease area and 

along the northern Gulf Coast. 

Species Scientific Name S

tatus 

Potential 

Presence Critical Habitat 

Designated in Gulf of 

Mexico Leas

e Area

Co

astal

Marine Mammals

Sperm whale Physeter macrocephalus E X -- None

West Indian 

manatee

Trichechus manatus 

latirostris E -- X Florida (Peninsular) 

Blue whale Balaenoptera musculus E X

a

-- None

Fin whale Balaenoptera physalus E X

a

-- None

Humpback whale Megaptera novaeangliae E X

a

-- None

North Atlantic 

right whale Eubalaena glacialis E X

a

 -- None 

Sei whale Balaenoptera borealis E X

a

-- None

Sea Turtles

Loggerhead 

turtle Caretta caretta T X X None 

Green turtle Chelonia mydas T

, Eb 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)

Smalltooth 

sawfish Pristis pectinata E -- X Southwest Florida and the Florida Keys

Invertebrates

Elkhorn coral Acropora palmata E -- X Flower Garden Banks

Terrestrial Mammals

Beach mice 

(Alabama, 

Choctawhatchee, 

Perdido Key, 

St. Andrew)

Peromyscus polionotus E -- X Alabama and Florida 

(Panhandle) beaches 

Abbreviations: E = endangered; T = threatened. 

a

 The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely 

to be present in the lease area. 

b

 The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered. 

Page 117 Public Information Copy
As mandated by the ESA, MMS consulted NMFS and the USFWS on possible and potential impacts from 

the proposed leasing in the Gulf of Mexico on endangered/threatened species and their designated 

critical habitat (MMS, 2007a,b). A Biological Assessment was prepared for each consultation. The formal 

ESA consultation with NMFS was concluded with receipt of the Biological Opinion on 3 July 2007 (NMFS, 

2007). The Biological Opinion concludes that the proposed lease sales and associated activities in the 

Five-Year Leasing Plan for Western and Central Planning Areas 2007-2012 are not likely to jeopardize the 

continued existence of threatened and endangered species under NMFS jurisdiction or destroy or 

adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded 

with a letter dated 14 September 2007. The USFWS concurred with MMS’s determination that proposed 

actions of the Five-Year Leasing Plan were not likely to adversely affect threatened/endangered species or 

designated critical habitat under USFWS jurisdiction. Following the Macondo spill, BOEMRE requested to 

reinitiate an ESA consultation with both NMFS and USFWS on 30 July 2010. The NMFS responded with a 

letter to BOEMRE on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 

27 September 2010. At present, the NMFS and USFWS have placed the consultation process on hold 

because they feel the environmental baseline information needs to be updated for the post-Macondo 

spill environment based on the results of the Natural Resource Damage Assessment (NRDA) process. The 

NRDA data have yet to be released, and the existing consultation remains in effect (BOEM, 2012b). The 

existing consultation recognizes that BOEM-required mitigations and other reasonable and prudent 

measures should reduce the likelihood of impacts from all BOEM-authorized activities in the Gulf of 

Mexico. 

Coastal endangered or threatened species that may occur along the northern Gulf Coast include the West 

Indian 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 in the MMS (2007b) and BOEM 

(2012b) lease sale EISs are no longer federally listed as endangered or threatened. These are discussed in 

Section C.4.2, Shorebirds and Coastal Nesting Birds. 

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 from the Gulf of Mexico but are considered rare or extralimital 

there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of 

Mexico. 

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 previous 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 NOAA Fisheries (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 northcentral 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 200- and 1,000-m (656- and 3,280-ft) depth contours (Jochens et al., 2008). Male sperm 

whales were more variable in their movements and were documented in water depths greater than 

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3,000 m (9,843 ft). 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). SWSS results show that sperm whales transit through the vicinity of the lease area. 

Movements of satellite-tracked individuals suggest that this area of the Gulf continental slope is within 

the home range of the Gulf of Mexico population (within the 95% utilization distribution) (Jochens et al., 

2008). 

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and 

helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). 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. 

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 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, 2011a; BOEM, 2012b). 

Impacts of Drilling Rig Presence, Noise, and Lights 

Noise generated from the drilling rig and from routine drilling activities has the potential to disturb sperm 

whales. 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. 

Sperm whales appear to have good low-frequency hearing, with variable responses to anthropogenic 

noise (Jochens et al., 2008). Southall et al. (2007) lists sperm whales in the same hearing group (i.e., midfrequency cetaceans) as dolphins, toothed whales, beaked whales, and bottlenose whales (estimated 

hearing range of 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 past 20 kHz has been reported, with source 

levels up to 236 dB re 1 μPa at 1 m. 

Sounds produced during drill rig 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, 2003b). Behavioral changes for marine 

mammals such as the sperm whale resulting from auditory masking sounds may include producing more 

calls, longer calls, or shifting the frequency of the calls (Holt et al., 2009; NMFS, 2009a). 

There are other OCS facilities and activities near the lease area, and the region as a whole has a large 

number of similar noise 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 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 remain stationary 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 individual whales with cues 

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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 Gulf of Mexico Oil and Gas Activities: Five-Year Leasing Plan for Western and Central Planning 

Areas 2007-2012 (NMFS, 2007). The analysis noted that drilling rigs emit 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). The NMFS (2009a) found 

that marine mammals in the Beaufort Sea that show behavioral avoidance for drilling activities were 

especially unlikely to incur auditory impairment or other physical injuries (75 FR 25741). 

Drilling rig lighting and rig presence are not identified as IPFs for sperm whales in lease sale EISs (MMS, 

2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), or the NMFS (2007) Biological 

Opinion. 

Impacts of Support Vessel and Helicopter Traffic 

Support vessel traffic has the potential to disturb sperm whales, and there is also a risk of vessel strikes, 

which are identified as a threat in the recovery plan for this species (NMFS, 2010a). Data concerning the 

frequency of vessel strikes are presented in a previous lease sale EIS (MMS, 2007b). To reduce the 

potential for vessel strikes, the BSEE and BOEM 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 91 m (300 ft) 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. 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 population level. With 

implementation of the vessel strike avoidance measures requirement to maintain a distance of 91 m 

(300 ft) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales 

would be reduced to discountable levels. 

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) documented 

responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an altitude of 245 m (800 ft). A 

reaction to the initial pass of the aircraft was observed during 3 (12%) of 24 sightings. All three reactions 

consisted of a hasty dive and occurred at less than 360 m (1,180 ft) 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. 

While flying offshore in the Gulf of Mexico, helicopters maintain altitudes above 213 m (700 ft) during 

transit to and from the working area. In the event that a whale is seen during transit, the helicopter will 

not approach or circle the animals. Although responses are possible (Smultea et al., 2008), the NMFS 

(2007) and BOEM (2012d) concluded that this altitude would minimize the potential for disturbing sperm 

whales. Therefore, no significant impacts are expected. 

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Impacts of a Small Fuel Spill 

Potential spill impacts on marine mammals including sperm whales are discussed in lease sale EISs (MMS, 

2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), and by NMFS (2007). Oil impacts 

on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP, there are no unique 

site-specific issues with respect to spill impacts on these animals that were not analyzed in the previous 

documents. 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP 

will mitigate and lessen the potential for impacts on sperm whales. Given the open ocean location of the 

lease area, the duration of a small spill and opportunity for impacts to occur would be very brief. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of 

impacts would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and 

indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), 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 (WCD) 

Potential spill impacts on marine mammals including sperm whales are discussed in lease sale EISs (MMS, 

2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), and by NMFS (2007). For this EP, 

there are no unique site-specific issues with respect to spill impacts on these animals. 

Impacts of oil spills on sperm whales can include 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. 

Complications of the above may lead to dysfunction of immune and reproductive systems, physiological 

stress, declining physical condition, and death. Behavioral responses can include displacement of animals 

from prime habitat, disruption of social structure, changing prey availability and foraging distribution 

and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or 

migration (MMC, 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. 

C.3.2 West Indian Manatee (Endangered) 

Most of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001). Manatee 

sightings in Louisiana have increased as the species extends its presence farther west of Florida in the 

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warmer months (Wilson, 2003). A species description is presented in a previous lease sale EIS (MMS, 

2007b) and in the recovery plan for this species (USFWS, 2001). 

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). 

A small fuel spill in the lease area would be unlikely to affect manatees, as the lease area is approximately 

261 km (162 miles) 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. 

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, BSEE and BOEM 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 this NTL will minimize the likelihood 

of vessel strikes, and no significant impacts on manatees are expected. 

Helicopter traffic 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 20 to 160 m (66 to 525 ft). Helicopters used in support operations maintain a 

minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or 

across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges 

and park properties. In addition, guidelines and regulations specify that helicopters maintain an altitude 

of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). This mitigation measure 

will minimize the potential for disturbing manatees, and no significant impacts are expected. 

Impacts of a Large Oil Spill (WCD) 

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as 

well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and 

dispersants) (MMC, 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 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, changing prey availability and foraging distribution and/or patterns, 

changing reproductive behavior/productivity, and changing movement patterns or migration 

(MMC, 2011). 

In the event that a large spill reached coastal waters where manatees were present, the level of vessel 

and aircraft activity associated with spill response could disturb manatees and potentially result in vessel 

strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 

2012-JOINT-G01 to reduce the potential for striking or disturbing these animals, and therefore no 

significant impacts are expected. 

C.3.3 Endangered Mysticete Whales 

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, 

and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital 

there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of 

Mexico. 

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Because of the rare occurrence of these whales in the Gulf of Mexico and the limited scope and duration 

of the project, it is highly unlikely that any endangered mysticete would come into contact with any 

project activities, either routine operations or accidents. NMFS did not include any of these mysticete 

whales as affected species in its Biological Opinion (NMFS, 2007). Potential impacts are analyzed in lease 

sale EISs (MMS, 2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d), and those 

analyses are incorporated by reference. If any of these whales were present in the area, potential 

impacts would be the same as those discussed below in Section C.3.4. 

C.3.4 Non-Endangered Marine Mammals (Protected) 

Excluding the seven endangered species that have been cited previously, there are 22 additional species 

of marine mammals that may be found in the Gulf of Mexico, including 2 species of mysticete whales, 2 

species of sperm whales, 4 species of beaked whales, and 14 species of delphinids. All marine mammals 

are protected species under the MMPA. The most common nonendangered cetaceans in the deepwater 

environment are odontocetes such as the pantropical spotted dolphin, spinner dolphin, and Clymene 

dolphin. A brief summary is presented below, and additional information on these groups is presented in 

a previous lease sale EIS (MMS, 2007b). 

Mysticete whales. Two species of nonendangered mysticete whales are known from the Gulf of Mexico. 

The Bryde’s whale (Balaenoptera edeni) has been sighted most frequently along the 100-m (328-ft) 

isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto 

Canyon region and off western Florida, although there have been some in the west-central portion of the 

northeastern Gulf. The minke whale (Balaenoptera acutorostrata) is considered rare in the Gulf of 

Mexico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the 

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). Either species could occur in the lease area. 

Beaked whales. Four species of beaked whales are known from 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 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 water depths greater than 1,000 m 

(3,281 ft) over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in 

the lease area. 

Delphinids. Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted 

dolphin (Stenella frontalis), bottlenose dolphin (Tursiops truncatus), Clymene dolphin (Stenella clymene), 

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

orca), melon-headed whale (Peponocephala electra), pantropical spotted dolphin (Stenella attenuata), 

pygmy killer whale (Feresa attenuata), short-finned pilot whale (Globicephala macrorhynchus), Risso’s 

dolphin (Grampus griseus), rough-toothed dolphin (Steno bredanensis), spinner dolphin (Stenella 

longirostris), and striped dolphin (Stenella coeruleoalba). Any of these species could occur in the lease 

area. The most common nonendangered cetaceans in the deepwater environment are the pantropical 

spotted dolphin, spinner dolphin, and Clymene dolphin. 

The bottlenose dolphin (Tursiops truncatus) is a common inhabitant of the northern Gulf of Mexico, 

particularly within continental shelf waters. There are two ecotypes of bottlenose dolphins, a coastal 

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form and an offshore form, which are genetically isolated from each other (Waring et al., 2012). 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 into 37 geographically distinct 

population units, or stocks, for management purposes by the NMFS (Waring et al., 2012). NMFS (2013) 

has proposed to classify the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of 

the Bay, Sound, and Estuarine Stocks as strategic stocks. A “strategic” stock is defined by the MMPA as a 

marine mammal stock: 

• 1. for which the level of direct human-caused mortality exceeds the potential biological removal 

level; 

• 2. that, 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 

• 3. that 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” of unprecedented size and duration that has affected these stock areas. This unusual 

mortality event began in February 2010 and is ongoing. 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 nonendangered 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 

(WCD). 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 

(toothed whales and dolphins) use higher-frequency sounds than those produced by OCS drilling activities 

(Richardson et al., 1995). Noise intensity associated with drilling is relatively weak, and the noise 

exposure of an individual animal would be transient. Stronger noise levels will occur during thruster use 

in dynamic positioning. 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 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 drill 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 and short duration of drilling activities, this project 

would represent a small temporary contribution to the overall noise regime, and any short-term impacts 

are not expected to be biologically significant to marine mammal populations. 

Drilling rig lighting and rig presence are not identified as IPFs for marine mammals in lease sale EISs (MMS, 

2007b; BOEM, 2012a,b) and the current Programmatic EIS (BOEM, 2012d). 

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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, BSEE and BOEM 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 maintain a distance of 91 m (300 ft) or greater when whales are sighted 

and 45 m (150 ft) 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 NTL 2012-JOINT-G01 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 213 m (700 ft) during transit to and from the working 

area. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m (1,000 

ft) within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). Maintaining this altitude will minimize the 

potential for disturbing marine mammals, and no significant impacts are expected (BOEM, 2012a,d). 

Impacts of a Small Fuel Spill 

Potential spill impacts on marine mammals are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), 

and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For this EP, 

there are no unique site-specific issues with respect to spill impacts on these animals. 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP is expected to lessen the 

potential for impacts on marine mammals. EP Section 9 provides detail on spill response measures, along 

with a summary of those measures in this EIA. Given the open ocean location of the lease area, the 

limited duration of a small spill, and response efforts, it is expected that any impacts would be brief and 

minimal. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of 

impacts would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and 

indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), 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 would be expected. 

Impacts of a Large Oil Spill (WCD) 

Potential spill impacts on marine mammals are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b). 

For this EP, there are no unique site-specific issues. Impacts of oil spills on marine mammals can include 

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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 

vegetation, in the case of manatees); and stress from the activities and noise of response vessels and 

aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, 

physiological stress, declining physical condition, and death. Behavioral responses can include 

displacement of animals from prime habitat, disruption of social structure, changing prey availability and 

foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing 

movement patterns or migration (MMC, 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. 

C.3.5 Sea Turtles (Endangered/Threatened) 

Five species of endangered or threatened sea turtles may be found near the lease area. Leatherback 

(Dermochelys coriacea), Kemp's ridley (Lepidochelys kempii), and hawksbill (Eretmochelys imbricata) 

turtles are endangered. The loggerhead turtle (Caretta caretta) is currently a threatened species; 

however, in March 2010, NMFS and USFWS proposed to list the Northwest Atlantic Ocean population of 

loggerhead turtles as endangered (75 FR 12598). The green turtle (Chelonia mydas) is listed as 

threatened, except for the Florida and Pacific coast of Mexico breeding populations, which are listed as 

endangered. Species descriptions are presented in MMS (2007b). 

The extent and scope of the Macondo spill represents new information not assessed in the existing ESA 

Section 7 consultation. As a result of this new information, BOEMRE reinitiated ESA Section 7 

consultation with NMFS and the USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE 

on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 27 September 2010. 

However, NMFS and the USFWS have placed the consultation process on hold pending the results of the 

NRDA post-Macondo spill data review, which has yet to be released. The existing consultation currently 

remains in effect (BOEM, 2012b). 

BOEMRE (2011a) and BOEM (2012b) reexamined the impacts analyses presented in MMS (2007b, 2008) 

for the five sea turtle species that inhabit the Gulf of Mexico based on additional information and in 

consideration of the Macondo spill. No new information was found that would alter the potential impacts 

on sea turtles described in previous EISs. In most foreseeable cases, exposure to hydrocarbons persisting 

in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased health, 

reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles. 

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 turtle species may be present 

in deepwater areas, including the lease area, where they may be associated with Sargassum and other 

flotsam. 

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

• Loggerhead turtles – Loggerheads nest in significant numbers along the Florida Panhandle and, to a 

lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant nesting area of 

loggerhead turtles is found in Louisiana, on beaches within the Breton NWR; 

• Green and leatherback turtles – Green and leatherback turtles infrequently nest on Florida Panhandle 

beaches (Florida Fish and Wildlife Conservation Commission, 2012); 

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• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas, 

Mexico (NMFS et al., 2011). 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, 2010); and 

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

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and 

helicopter traffic; and two types of accidents–a small fuel spill and a large oil spill (WCD). 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/or visual disturbances. The most likely 

impacts would be short-term behavioral changes such as diving and evasive swimming, disruption of 

activities, or departure from the area. Due to the limited scope and short duration of drilling activities, 

these short-term impacts are not expected to be biologically significant to sea turtle populations. 

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 1997; 

Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they are offshore than 

when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that 

the effects of lighting from offshore structures on sea turtles are insignificant. 

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, BSEE and BOEM issued NTL 2012-JOINTG01, 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 45 m 

(150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel 

strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007). 

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters 

maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will 

minimize the potential for disturbing sea turtles, and no significant impacts are expected. 

Impacts of a Small Fuel Spill 

Potential spill impacts on sea turtles are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and 

the NMFS Biological Opinion (NMFS, 2007). For this EP, there are no unique site-specific issues with 

respect to spill impacts on these animals. 

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The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP is expected to minimize 

potential impacts on sea turtles. EP Section 9 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 be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and 

weather conditions. 

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,d). However, due to the limited 

areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts 

would be expected. 

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches, as the lease area 

is 261 km (162 miles) 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 (WCD) 

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts 

due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and 

physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, 

and mucous membranes; inhalation of toxic fumes and smoke (e.g., from in situ burning of oil); ingestion 

of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of 

response vessels and aircraft. Complications of the above may lead to dysfunction of immune and 

reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses 

can include displacement of animals from prime habitat, disruption of social structure, changing food 

availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and 

changing movement patterns or migration. In the unlikely event of a spill, implementation of 

ExxonMobil’s OSRP is expected to minimize the potential for these types of impacts on sea turtles. 

EP Section 9 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). 

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). 

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In the event of a large spill, the level of vessel and aircraft activity associated with spill response could 

disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or stress. 

Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce the potential for 

striking or disturbing these animals, and therefore no significant impacts 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 3). Piping 

Plovers inhabit coastal sandy beaches and mudflats, feeding by probing for invertebrates at or just below 

the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A 

species description is presented in a previous lease sale EIS (MMS, 2007b). 

A large oil spill (WCD) 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). 

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Figure 3. Location of selected environmental features in relation to the lease area. 

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Impacts of a Large Oil Spill (WCD) 

The lease area is 262 km (163 miles) from the nearest shorelines inhabited by Piping Plovers (Figure 3). 

The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) summarized in Section A.9.3 (Table 3) predict 

that during the spring there is a 4% probability that an oil spill from the lease area would reach a shoreline 

designated as critical habitat for the Piping Plover within 10 days. Plovers could physically oil themselves 

while foraging on oiled shores or secondarily contaminate themselves 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. ExxonMobil has extensive resources 

available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in 

the OSRP. 

C.3.7 Whooping Crane (Endangered) 

The Whooping Crane (Grus americana) is an omnivorous wading bird and an endangered species. There 

are three wild populations in North America (Whooping Crane Eastern Partnership, 2010). One 

population winters along the Texas coast at Aransas NWR and summers at Wood Buffalo National Park in 

Canada; this population represents the majority of the world’s population of free-ranging Whooping 

Cranes and reached a record population of 270 at Aransas NWR in December 2008 (Whooping Crane 

Eastern Partnership, 2010). A nonmigrating 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). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise 

the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for 

the species. A species description is presented in lease sale EISs (MMS, 2007b; BOEM, 2012a). A large oil 

spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would 

also be unlikely to affect Whooping Cranes, due to the distance from Aransas NWR. As explained in 

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

breaking up. 

Impacts of a Large Oil Spill (WCD) 

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately 563 km (350 miles) 

from its critical habitat designated in the Aransas NWR. The revised OSRA modeling (BOEM, 2012b) 

predicts that there is a 3% or less probability that an oil spill originating in the lease area would reach the 

Aransas NWR within 30 days and a 17% probability of oil reaching that area in 120 days. 

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in oiled areas 

or secondarily contaminate themselves through ingestion of contaminated shellfish, frogs, and fishes. It is 

possible that some Whooping Crane deaths could occur. In the event of a spill, ExxonMobil would work 

with the applicable State and Federal agencies to prevent impacts from a spill. 

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 

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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, 2010b) (Figure 3). A species description is presented in a lease sale EIS (MMS, 2007b) and in the 

recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995). 

A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with 

routine project activities that could affect these fish. 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 (WCD) 

Potential spill impacts on Gulf sturgeon are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and 

by NMFS (2007). For this EP, there are no unique site-specific issues with respect to this species. 

The lease area is approximately 378 km (235 miles) from the nearest Gulf sturgeon critical habitat. The 

revised OSRA modeling (BOEM, 2012b) predicts that a spill in the lease area has 1% or less probability of 

contacting any coastal areas inhabited by Gulf sturgeon within 30 or 120 days. 

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion 

of oiled prey, or the absorption of dissolved petroleum products through the gills. Based on the life 

history of this species, subadult and adult Gulf sturgeon would be most vulnerable to an estuarine or 

marine oil spill, and would be vulnerable only from 1 September through 30 April when this species is 

foraging in estuarine and shallow marine habitats (NMFS, 2007). 

C.3.9 Smalltooth Sawfish (Endangered) 

Smalltooth sawfish (Pristis pectinata) are found in the tropical and subtropical Atlantic Ocean. In the 

Western Atlantic they have historically ranged from New York to Brazil, including the Gulf of Mexico and 

Caribbean Sea. This sawfish primarily occurs in estuarine and coastal habitats such as bays, lagoons, and 

rivers. The smalltooth sawfish was listed as endangered under the ESA on 1 April 2003. Its critical habitat 

consists of two units: the Charlotte Harbor Estuary Unit, which comprises approximately 89,621 ha 

(221,459 ac) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises 

approximately 250,506 ha (619,013 ac) of coastal habitat. The two units are located along the 

southwestern coast of Florida between Charlotte Harbor and Florida Bay. 

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish. There are no IPFs associated 

with routine project activities that could affect these fish. A small fuel spill in the lease area would be 

unlikely to affect smalltooth sawfish because a small fuel spill would not be expected to make landfall or 

reach coastal waters prior to breaking up (see Section A.9.2). 

Impacts of a Large Oil Spill (WCD) 

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine 

species in lease sale EISs (MMS, 2007b; BOEM, 2012a) and by the NMFS (2007) in its Biological Opinion. 

For this EP, there are no unique site-specific issues with respect to smalltooth sawfish. 

In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct ingestion, 

ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. 

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C.3.10 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 mice. Critical habitat has been designated for all four subspecies; Figure 3 shows the 

critical habitat combined for all four subspecies. Species descriptions are provided in a previous lease sale 

EIS (MMS, 2007b). 

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with 

routine project activities that could affect these animals due to the distance from shore and the lack of 

any onshore support activities near their habitat. A small fuel spill in the lease area would not affect 

beach mice because a small fuel spill would not be expected to make landfall or reach coastal waters prior 

to breaking up (see Section A.9.2). 

Impacts of a Large Oil Spill (WCD) 

Potential spill impacts on beach mice are discussed in lease sale EISs (MMS, 2007b, 2008; BOEMRE, 

2011a; BOEM, 2012a). For this EP, there are no unique site-specific issues with respect to these species 

that were not analyzed in those documents. 

The lease area is about 493 km (306 miles) northeast from the nearest beach mouse critical habitat. The 

revised OSRA modeling summarized in Section A.9.3 predicts that a spill in the lease area has a 1% or less 

probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 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. However, any such 

impacts are unlikely due to the distance from shore and response actions that would occur in the event of 

a spill. 

C.3.11 Elkhorn Coral (Endangered) 

Elkhorn coral (Acropora palmata) is found primarily in shallow waters with temperatures ranging between 

26°C and 30°C (79°F and 86°F) and significant water movement. Elkhorn coral was once one of the most 

abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in tropical and subtropical 

waters. In the northern Gulf of Mexico, elkhorn coral has been found within the coral cap region of the 

Flower Garden Banks National Marine Sanctuary (Flower Garden Banks National Marine Sanctuary, 2011). 

There are no IPFs associated with routine project activities that could affect this species in the northern 

Gulf of Mexico. A small fuel spill would not affect elkhorn coral colonies because the oil would float and 

dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of the Flower Garden 

Banks because of the water depth of the area. Although subsurface plumes were reported following the 

Macondo spill, these plumes resulted from the use of subsea dispersants at the seafloor. 

C.4 Coastal and Marine Birds 

C.4.1 Marine Birds 

Marine birds include seabirds and other species that may occur in the pelagic environment of the project 

area (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives 

offshore over the open ocean, except during breeding season when they nest along the coast. In 

addition, other birds such as waterfowl, marsh birds, and shorebirds may occasionally be present over 

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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 Gulls, Royal Terns, 

Bridled Terns) (Hess and Ribic, 2000). The GulfCet II study did not estimate bird densities; however, 

Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km2. 

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 (Powers, 1987). 

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’s Shearwater (Puffinus lherminieri). Seabirds are distributed Gulf-wide and are not specifically 

associated with the lease area. 

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 rigs 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 (WCD). 

Effluent discharges permitted under the NPDES 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 rigs may be exposed to contaminants including air pollutants and routine discharges, 

but significant impacts are unlikely due to rapid dispersion. 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 rig collisions appear to be similar. In some cases, migrants simply do not see a 

part of the rig until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On 

the other hand, offshore structures are suitable stopover habitats for most trans-Gulf migrant species, 

and most of the migrants that stop over on rigs probably benefit from their stay, particularly in spring 

(Russell, 2005). Due to the limited scope and short duration of drilling activities described in this EP, any 

impacts on populations of either seabirds or trans-Gulf migrant birds are not expected to be significant. 

A study in the North Sea indicated that rig lighting causes circling behavior in various birds, especially on 

cloudy nights; apparently the birds’ geomagnetic compasses are upset by the red part of the spectrum 

from the lights currently in use (Nederlandse Aardolie Maatschappij, 2007). The numbers varied greatly, 

from none at all to some tens of thousands of birds per night per rig, with an apparent effect radius of up 

to 5 km (3 miles). Poot et al. (2008) found the magnetic compass of migratory birds to be 

wavelength-dependent. Migratory birds require light from the blue-green part of the spectrum for 

magnetic compass orientation, whereas red light (visible long-wavelength) disrupts their magnetic 

orientation. They designed a field study to test if and how changing light color influenced migrating birds 

under field conditions. During field studies they found that nocturnally migrating birds were disoriented 

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and attracted by red and white light (containing visible long-wavelength radiation), whereas they were 

clearly less disoriented by blue and green light (containing less or no visible long-wavelength radiation) 

(Poot et al., 2008). 

The OSPAR workshop (OSPAR Commission, 2012) noted that this circling increases the risk of collisions 

leading to traumas and deaths and may interrupt their migration. A study in the Gulf of Mexico also 

noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider in 

evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in 

the Gulf of Mexico versus the North Sea. 

Overall, potential negative impacts to birds 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, 2012a). 

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 lease sale EISs (MMS, 2007b; BOEM, 2012a,b) and 

the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with 

respect to spill impacts on these animals. 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP 

will reduce the potential for impacts on marine and pelagic birds. EP Section 9 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 be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and 

weather conditions. 

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 VOCs. Due to the 

limited areal extent and short duration of water quality impacts from a small fuel spill, secondary impacts 

due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the 

low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface 

slick, no significant impacts on pelagic birds would be expected. 

Impacts of a Large Oil Spill (WCD) 

Potential spill impacts on marine and pelagic birds are discussed in lease sale EISs (MMS, 2007b; BOEM, 

2012 a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific 

issues with respect to spill impacts on these animals. 

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BOEM has reexamined the analyses for coastal and marine birds presented in MMS (2007b, 2008) and 

determined that no new information was found that would alter the potential impacts on marine and 

pelagic birds (BOEMRE, 2011a; BOEM, 2012b). 

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported 

that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the 

deepwater Gulf of Mexico (>200 m [>656 ft]). 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. 

The recent Macondo spill provides relevant information about the species of pelagic birds that may be 

affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic 

species such as the Northern Gannet, Magnificent Frigatebird, and Masked Booby (USFWS, 2011). The 

Northern Gannet is among the species with the largest numbers of birds affected by the spill. 

C.4.2 Shorebirds and Coastal Nesting Birds 

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed 

previously in Section C.3. Various species of non-endangered birds are also found along the northern Gulf 

Coast, including diving birds, shorebirds, marsh birds, wading birds, and waterfowl. Gulf Coast marshes 

and beaches also provide important feeding grounds and nesting habitats. Species that nest on beaches, 

flats, dunes, bars, barrier islands, and similar coastal and nearshore 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 lease sale EISs (MMS, 2007b; BOEM, 2012a). 

The Brown Pelican (Pelecanus occidentalis) was delisted from Federal endangered status in 2009 

(USFWS, 2010c). However, this species remains listed as endangered by the State of Louisiana (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, 2011), and is listed as a 

species of special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 

2011). Brown Pelicans inhabit coastal habitats and forage within both coastal waters and waters of the 

inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that 

Brown Pelicans do not occur in 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). 

The Southern Bald Eagle (Haliaeetus leucocephalus) was delisted from its threatened status in the lower 

48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern 

U.S., including coastal habitats along the Gulf of Mexico. The Gulf Coast is inhabited by both wintering 

migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992). 

IPFs potentially affecting shorebirds and coastal nesting birds include support vessel and helicopter traffic 

and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect shorebirds or 

coastal nesting birds, as the lease area is 261 km (162 miles) from the nearest shoreline. As explained in 

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

breaking up. Compliance with NTL 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, 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). 

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Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between species and 

between individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds 

away from vessel pathways; known distances are from 20 to 49 m (65 to 160 ft) for personal watercraft 

and 23 to 58 m (75 to 190 ft) for an outboard-powered boat (Rodgers and Schwikert, 2002). Flushing 

distances may be similar or less for the support vessels to be used for ExxonMobil’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 disturbances to nesting birds, eggs, and chicks is not expected. 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 and short duration of drilling activities, any 

short-term impacts are not expected to be significant to coastal bird populations. 

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly 

dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, 

and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most 

intense responses over other human disturbances (Bélanger and Bédard, 1989). The Federal Aviation 

Administration recommends (Advisory Circular No. 91-36D) that pilots maintain a minimum altitude of 

610 m (2,000 ft) when flying over noise-sensitive areas such as parks, forest, primitive areas, wilderness 

areas, National Seashores, or National Wildlife Refuges, and maintain flight paths to reduce aircraft noise 

in these noise-sensitive areas. The altitude minimum is greater than the distance (slant range) at which 

aircraft overflights have been reported to cause behavioral effects on most species of birds studied by 

Efroymson et al. (2000). It is assumed that adherence to these guidelines would reduce potential 

behavioral disturbances (such as temporary displacement or avoidance behavior) of individual birds in 

coastal and inshore areas. The potential impacts are not expected to be significant to bird populations or 

species in the project area. 

Impacts of Large Oil Spill (WCD) 

Data from the Macondo spill provide additional information about the species of coastal birds that may 

be affected in the event of a catastrophic spill of a similar nature and duration. This information 

supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and 

based on the latest reports, about 5,000 dead birds have been collected since the spill began, and about 

1,900 of the dead animals were visibly oiled. In addition, over 2,000 oiled birds have been collected alive 

and about 1,200 released (NMFS, 2010c). According to the USFWS (2011), bird species that have been 

treated for oiling include the following: 

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• Brown Pelican 

• White Pelican 

• Masked Booby 

• Magnificent Frigatebird 

• Laughing Gull 

• Herring Gull 

• Northern Gannet 

• Black Crowned Night Heron 

• Tri-colored Heron 

• Green Heron 

• Cattle Egret 

• Snowy Egret 

• Reddish Egret 

• Least Bittern 

• Common Tern 

• Royal Tern 

• Caspian Tern 

• Sandwich Tern 

• Forster’s Tern 

• Black Tern 

• Gull-billed Tern 

• Least Tern 

• Black Skimmer 

• Black Oystercatcher 

• White Ibis 

• Roseate Spoonbill 

• Willet 

• Sanderling 

• Dunlin 

• Semipalmated Sandpiper 

• Killdeer 

• King Rail 

• Clapper Rail 

• Virginia Rail 

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were Laughing Gull, 

Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and 

unidentified Tern. There are no reports of Bald Eagle oiling. 

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). Modeling of Macondo spill-related bird impacts is 

underway by NRDA, but results have not yet been released. Antonio et al. (2011) modeled bird mortality 

from the Macondo spill showing cumulative carcass numbers and mortality rate increasing exponentially 

from the start of the Macondo spill until the mortality rate began to decline after the 97th day of the spill. 

Note that the collected animals would be a small subset of the total number of impacted birds, and 

therefore the collected animals would represent an underestimated measure of the overall impact of the 

Macondo event (BOEM, 2012b). 

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or wade in 

oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which 

could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency of feathers and can 

cause hypothermia in the right conditions. As birds groom themselves, they can ingest and inhale the oil 

on their bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carcasses of 

contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, 

liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the 

nest. 

As noted above, the Brown Pelican was recently removed from the Federal endangered species list. Over 

300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These 

data indicate that Brown Pelicans may be particularly at risk of oiling in the event of a catastrophic spill 

reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup 

activities, and long-term habitat contamination. 

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C.5 Fisheries Resources 

C.5.1 Pelagic Communities and Ichthyoplankton 

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater environment of 

the northern Gulf of Mexico. The biological oceanography of the region is dominated by the influence of 

the Loop Current, whose surface waters are among the most oligotrophic in the world’s oceans. 

Superimposed on this low-productivity condition are productive "hot spots" associated with entrainment 

of nutrient-rich Mississippi River water and mesoscale oceanographic features. Anticyclonic and cyclonic 

hydrographic features play an important role in determining biogeographic patterns and controlling 

primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000). 

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae 

(Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the 

planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 

2007b). 

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, 

and lights; effluent discharges; water intakes; and two types of accidents–a small fuel spill and a large oil 

spill (WCD). 

Impacts of Drilling Rig Presence, Noise, and Lights 

The drilling rig, as a floating structure in the deepwater environment, will act as a fish-attracting device 

(FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, 

dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures 

(Holland et al., 1990; Higashi, 1994; Relini et al., 1994; MMS, 2000, 2007b, 2008). This FAD effect could 

possibly enhance the feeding of epipelagic predators by attracting and concentrating smaller fish species. 

Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or 

adverse, are considered minor. 

Impacts of Effluent Discharges 

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the 

immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic 

matter, and chlorine, but should 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 should 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 the ocean for once-through, non-contact cooling of machinery on the 

drillship. The drillship considered for use for activities described in this EP is a "new" facility as defined by 

the NPDES permit and therefore will comply with the cooling water intake regulations for Phase III 

facilities under Section 316(b) of the Clean Water Act. 

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The intake of seawater for cooling water will entrain plankton. The low intake velocity should allow most 

strong-swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, 

drifting plankton would not be able to escape entrainment with the exception of a few fast-swimming 

larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily 

through changes in water temperature during the route from cooling intake structure to discharge 

structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and 

short duration of drilling activities, any short-term impacts of entrainment are not expected to be 

biologically significant to plankton or ichthyoplankton populations. 

Impacts of a Small Fuel Spill 

Potential spill impacts on fisheries resources are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) 

and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues 

with respect to spill impacts. 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP 

will mitigate the potential for impacts on pelagic communities, including ichthyoplankton. EP Section 9 

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 be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and 

weather conditions. 

A small fuel spill could have localized impacts on phytoplankton, zooplankton, 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 (WCD) 

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 are especially vulnerable to oiling because 

they inhabit the upper layers of the water column, and they will die if exposed to certain toxic fractions of 

spilled oil. Impacts potentially would be greater if local-scale currents retained planktonic larval 

assemblages (and the floating oil slick) within the same water mass. 

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 BOEM (2012b) has reexamined the analysis for fish resources and EFH presented in lease EISs (MMS, 

2007a,b), in consideration of the Macondo event. No substantial new information was found that would 

alter the impact conclusions for fish resources and EFH presented in MMS (2007a,b). 

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The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management Plans for 

corals and coral reefs, shrimps, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and 

red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the 

various Fishery Management Plans (GMFMC, 2005). The EFH for most of these GMFMC-managed species 

is on the continental shelf in waters shallower than 183 m (600 ft). 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 are located 

approximately 132 km (82 miles) north-northwest of the lease area along the shelf edge south of 

Louisiana. 

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group 

for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, 

swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near 

the lease area include the following species and life stages (NMFS, 2009b):

• Albacore tuna (adults) 

• Atlantic bluefin tuna (spawn, eggs, 

larvae, adults) 

• Bigeye tuna (adults) 

• Bigeye thresher shark (all) 

• Blue marlin (juveniles, adults) 

• Longbill spearfish (juveniles, adults) 

• Longfin mako shark (all) 

• Oceanic whitetip shark (all) 

• Skipjack tuna (spawn, adults) 

• Swordfish (larvae, juveniles, adults) 

• White marlin (juveniles, adults) 

• Yellowfin tuna (spawn, juveniles, 

adults) 

Recent research indicates the central and western Gulf of Mexico may be important spawning habitat for 

Atlantic bluefin tuna, and NMFS (2009b) has designated a Habitat Area of Particular Concern (HAPC) for 

this species. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area (Figure 3). 

The areal extent of the HAPC is approximately 300,000 km2 (15,000 mi2). The prevailing assumption is 

that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern U.S. 

and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in April, May, and June (NMFS, 

2009b). 

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin tuna 

currently do not warrant species protection under the ESA. However, NOAA did classify the bluefin tuna 

as a species of concern, effectively placing bluefin tuna on a watch list as the agency awaits new data on 

the impact of a stricter international management regimen. 

A new amendment to the original EFH Generic Amendment was finalized in 2005 (GMFMC, 2005). One of 

the most significant proposed changes in this amendment reduced the extent of EFH relative to the 1998 

Generic Amendment by removing the EFH description and identification from waters between 100 

fathoms and the seaward limit of the Exclusive Economic Zone (EEZ). The Highly Migratory Species 

Fisheries Management Plan was amended in 2009 to update EFH and HAPC to include the bluefin tuna 

spawning area (NMFS, 2009b). 

There are current NTLs (2009-G39 and 2009-G40) that provide guidance and clarification of the 

regulations with respect to biologically sensitive underwater features and areas and benthic communities 

that are considered EFH (MMS, 2009a,b). A new EFH consultation has been initiated between BOEM’s 

Gulf of Mexico Region and NOAA’s Southeastern Region. Some EFH requirements may change with the 

new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the 

elements described above will be followed (BOEMRE, 2011a; BOEM, 2012b). 

Other HAPCs have been identified by the GMFMC (2005). These include the Florida Middle Grounds, 

Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, and 

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several individual reefs and banks of the northwestern Gulf of Mexico (Figure 3). The nearest HAPC is 

Jakkula Bank, located approximately 150 km (93 miles) north-northwest of the lease area. 

IPFs potentially affecting EFH 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 (WCD). 

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; MMS, 2000, 2007b, 2008). This FAD effect would possibly enhance 

feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling 

rig is a single, temporary structure, any impacts on EFH for highly migratory pelagic fishes are considered 

minor. 

Impacts of Effluent Discharges 

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling muds 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 and short duration of drilling activities, 

any short-term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically 

significant. 

Impacts of a Small Fuel Spill 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP 

will help diminish the potential for impacts on EFH. EP Section 9 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. 

Potential spill impacts on EFH are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) and the 

current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with 

respect to spill impacts. 

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of 

impacts would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and 

indicates that over 90% would be evaporated or dispersed naturally within 24 hours. The area of the sea 

surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac), depending on sea state and 

weather conditions. 

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, 

swordfishes, billfishes, and 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 bluefin tuna, which covers much of 

the deepwater Gulf of Mexico. The areal extent of the affected area would represent a negligible portion 

of the HAPC. 

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A small fuel spill would not affect EFH for corals and coral reefs, the nearest of which is the topographic 

features located approximately 132 km (82 miles) from the lease area along the shelf edge south of 

Louisiana. A small fuel spill would float and dissipate on the sea surface and would not contact these 

features. 

Impacts of a Large Oil Spill (WCD) 

Potential spill impacts on EFH are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a) and the 

current Programmatic EIS (BOEM, 2012d). For this EP, 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 in the subsurface as well. Given the extent of EFH designations in the Gulf of 

Mexico (GMFMC, 2005; NMFS, 2009b), some impact on EFH would be unavoidable. 

A large spill could affect the EFH for many managed species including shrimps, stone crab, spiny lobster, 

reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water 

quality and water column biota including phytoplankton, zooplankton, and nekton. In coastal waters, 

sediments could be contaminated and result in persistent degradation of the seafloor habitat for 

managed demersal fish and shellfish species. 

The lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009b). 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. 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, 

2009b). 

The topographic features located 132 km (82 miles) north-northwest of the lease area are designated as 

EFH under the corals and coral reefs management plan. An accidental spill would be unlikely to affect this 

area, since a surface slick would not reach these features because of their depth. 

C.6 Archaeological Resources 

C.6.1 Shipwreck Sites 

The BOEM (2012b) reexamined the analyses for archaeological resources presented in MMS (2007b, 

2008), based on additional information available since the publication of these two documents and in 

consideration of the Macondo oil spill. Substantial new information that alters the impact conclusion for 

archaeological resources presented in MMS (2007b, 2008) 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 (656 ft) deep that have been exempted from highresolution surveys. Since significant historic shipwrecks have recently been discovered outside the 

previously designated high-probability areas (some of which show evidence of impacts from permitted 

activities prior to their discovery), a survey is now required for exploration and development projects. 

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012c). 

A total of 24 unidentified sonar contacts was recorded during the archaeological assessment of the lease 

area; these sonar contacts were not recommended for archaeological avoidance or investigation, and the 

assessment area was interpreted to be absent of potential archaeological resources (C & C Technologies, 

Inc., 2012). 

ExxonMobil will abide by the applicable requirements of NTL 2005-G07, which stipulate that work be 

stopped at the project site if any previously undetected archaeological resource is discovered after work 

has begun until appropriate surveys and evaluations have been completed. 

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Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect 

shipwrecks. Impacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not 

affect shipwrecks because the oil would float and dissipate on the sea surface. 

Impacts of a Large Oil Spill (WCD) 

MMS (2007b) estimated that a severe subsurface blowout could resuspend and disperse sediments within 

a 300-m (984-ft) radius. Because there are no historic shipwrecks in the lease area, this impact would not 

be relevant. 

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological 

sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because 

the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo 

spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 35 

km (22 miles) from the wellsite and persisting for more than a month (Camilli et al., 2010). The 

subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 

2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume 

could have the potential to contact shipwreck sites beyond the 300-m (984-ft) radius estimated by MMS 

(2007a, 2008), depending on its extent, trajectory, and persistence. If oil from a subsea spill should come 

into contact with wooden shipwrecks on the seafloor, it could adversely affect their condition or 

preservation. Should there be any indication that potential shipwreck sites could be affected, in 

accordance with NTL 2005-G07 ExxonMobil will immediately halt operations, take steps to ensure that the 

site is not disturbed in any way, and contact the BOEM Regional Supervisor, Leasing and Environment, 

within 48 hours of its discovery. ExxonMobil would cease all operations within 305 m (1,000 ft) of the site 

until the Regional Supervisor provides instructions on steps to take to assess the site’s potential historic 

significance and protect it. 

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. As 

noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the 

major impact would be a temporary, reversible visual impact from oil contact and contamination of the 

site and its environment. 

C.6.2 Prehistoric Archaeological Sites 

Available evidence suggests that sea level in the northern Gulf of Mexico was at least 91 m (300 ft), and 

possibly as much as 130 m (427 ft), lower than present sea level during the period 20,000 to 17,000 years 

Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand 

around 3,500 years B.P. (Pearson et al., 1986). 

During periods that the continental shelf was exposed above sea level, the area was open to habitation by 

prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently accepted to be 

around 12,000 years B.P. (Aten, 1983). The sea-level curve for the northern Gulf of Mexico proposed by 

Coastal Environments, Inc. suggests that sea level at 12,000 years B.P. would have been approximately 45 

to 60 m (148 to 197 ft) below the present-day sea level (Coastal Environments, Inc., 1977, 1982). On this 

basis, the continental shelf shoreward of the 45- to 60-m (148- to 197-ft) bathymetric contours has 

potential for prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the 

depth of sea level and the entry date of prehistoric man into North America, the MMS adopted the 60-m 

(197-ft) water depth as the seaward extent for archaeological site potential in Gulf of Mexico region. 

With a water depth of approximately 1,937 m (6,354 ft), the lease area is well beyond the 60-m (197-ft) 

depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the 

Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant 

IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources 

because the oil would float and dissipate on the sea surface. 

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Impacts of a Large Oil Spill (WCD) 

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the 

physical effects of a subsea blowout. The MMS (2007b) estimates that a severe subsurface blowout could 

resuspend and disperse sediments within a 300-m (984-ft) 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). If a spill did reach a prehistoric site along 

these shorelines it could coat fragile artifacts or site features and compromise the potential for 

radiocarbon dating organic materials in a site (although other dating methods are available and it is 

possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be 

damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of 

artifacts and site features). BOEM (2012a) notes that some unavoidable direct and indirect impacts on 

coastal historic resources could occur resulting in the loss of information. 

C.7 Coastal Habitats and Protected Areas 

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities are 

described in lease sale EISs (MMS, 2007b; BOEM, 2012a,b), the current Programmatic EIS (BOEM, 2012d), 

and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include 

barrier beaches and dunes, wetlands, and submerged seagrass beds. Generally, most of the northeastern 

Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered 

areas behind the barrier islands and in estuaries. 

Due to the distance from shore, the only IPF associated with routine activities in the lease area that 

potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness 

areas, or any other managed or protected coastal area relates to support vessel traffic. The support bases 

at Port Fourchon, Louisiana, are not in wildlife refuges or wilderness areas. Potential impacts of support 

vessel traffic are addressed briefly below. 

A small fuel spill in the lease area would be unlikely to affect coastal habitats, as the lease area is 261 km 

(162 miles) 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 Support Vessel Traffic 

For OCS activities in general, support operations, including crew boats and supply boats, may have a 

minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes 

can erode shorelines along inlets, channels, and harbors. Support operations, including crew boats and 

supply boats as detailed in EP 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 (WCD) 

Potential spill impacts on coastal habitats are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) 

and the current Programmatic EIS (BOEM, 2012d). Coastal habitats inshore of the project area include 

barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP, there are no unique 

site-specific issues with respect to coastal habitats. 

The revised OSRA modeling summarized in Table 3 predicts that during winter there is a 17% probability 

of oil from a spill in the lease area reaching shorelines in Texas within 120 days, and a 14% probability in 

spring of oil reaching Louisiana shorelines within 120 days. 

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The shorelines within the geographic range predicted by the OSRA modeling (Table 3) 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 lease 

sale EISs (MMS, 2007b; BOEM, 2012b) and ExxonMobil’s OSRP. Coastal and near coastal wildlife refuges, 

wilderness areas, and State and National parks within the geographic range of the potential shoreline 

contacts after 120 days are presented in Table 6.

Table 6. Wildlife refuges, wilderness areas, and State and National parks within the geographic range of 

the potential shoreline contacts after 120 days (From: BOEM, 2012b). 

County or Parish, State Wildlife Refuge, Wilderness Area, or

State/National Park 

Cameron County, Texas 

Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore 

Isla Blanca Park 

Andy Bowie County Park 

Laguna Madre Estuarine and Coastal Marine Area 

Willacy County, Texas 

Lower Rio Grande Valley National Wildlife Reserve 

Laguna Atascosa National Wildlife Reserve 

Padre Island National Seashore 

Laguna Madre Estuarine And Coastal Marine Area 

Kenedy County, Texas Padre Island National Seashore 

Laguna Madre Estuarine and Coastal Marine Area 

Kleberg County, Texas Padre Island National Seashore

Laguna Madre Estuarine and Coastal Marine Area 

Nueces County, Texas 

Laguna Madre Estuarine and Coastal Marine Area 

Mustang Island State Park 

Lake Corpus Christi State Park 

Port Aransas Park 

Mission-Aransas National Estuarine Research Reserve 

Aransas County, Texas 

Mission-Aransas National Estuarine Research Reserve 

Aransas National Wildlife Refuge 

Goose Island State Park 

Calhoun County, Texas 

Mission-Aransas National Estuarine Research Reserve 

Aransas National Wildlife Refuge 

Matagorda Island State Park 

Guadalupe Delta Wildlife Management Area 

Welder Flats Coastal Preserve 

Matagorda County, Texas 

Big Boggy National Wildlife Refuge 

Aransas National Wildlife Refuge 

Mad Island Wildlife Management Area 

San Bernard National Wildlife Refuge 

Brazoria County, Texas 

San Bernard National Wildlife Refuge 

Peach Point Wildlife Management Area 

Brazoria National Wildlife Refuge 

Christmas Bay Coastal Preserve and Christmas Bay State Park 

Galveston County, Texas 

Galveston Island State Park 

Brazoria National Wildlife Refuge 

Apffel Park 

Seawolf Park 

Old Fort Travis Park 

Atkinson Island Wildlife Management Area 

Ft. Anahuc Park 

Anahuac National Wildlife Refuge 

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County or Parish, State Wildlife Refuge, Wilderness Area, or

State/National Park

McFaddin National Wildlife Refuge 

Jefferson County, Texas 

McFaddin National Wildlife Refuge 

Sea Rim State Park 

Murphree Wildlife Management Area 

Texas Point National Wildlife Refuge 

Cameron Parish, Louisiana 

Sabine National Wildlife Refuge 

Cameron Prairie National Wildlife Refuge 

Lacassine National Wildlife Refuge 

Little Pecan Island Natural Area 

Peveto Woods Natural Area 

Lower Neches Wildlife Management Area 

Rockefeller Wildlife Management Area 

Vermilion Parish, Louisiana Louisiana Rockefeller Wildlife Management Area 

Paul J. Rainey Wildlife Management Area 

Plaquemines Parish, Louisiana 

Salvador Wildlife Management Area 

Jean Lafitte National Historical Park and Preserve 

Delta National Wildlife Refuge 

Pass-a-Loutre Wildlife Management Area 

Breton National Wildlife Refuge 

St. Bernard State Park 

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The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, 

the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 

2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil-and-water mousse, or tarballs 

(MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil 

that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or 

aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying 

depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may 

also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up 

manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist for 

several years as it slowly biodegrades and volatilizes. 

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting 

wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation will experience dieback. Thirty percent of these 

damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the 

contacted wetlands are expected to be converted permanently to open-water habitat. The critical 

concentration of oil is that concentration above which impacts to wetlands will be long-term and recovery will 

take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. 

Critical concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. 

Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high 

cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshes may 

accelerate rates of erosion and retard recovery rates, which have been reported to require from years to 

decades following a spill (MMS, 2007b; BOEMRE, 2011a; BOEM, 2012b). 

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, 2008) 

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, 2011a; BOEM, 2012b). 

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for 

tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has 

occurred historically in the project area, primarily during spring and summer. In August 2000, the Federal 

government closed two areas in the northeastern Gulf of Mexico to longline fishing (65 FR 47214, 

1 August 2000). The lease is outside of the closure areas. 

Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 

to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are 

clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to 

retrieve it. Longlines are often set near oceanographic features such as fronts or downwellings, with the aid of 

sophisticated on-board temperature sensors, depth finders, and positioning equipment. Vessels typically are 

10 to 30 m (33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main Gulf of Mexico homeports 

for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City). 

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. 

Benthic species targeted by commercial fishers occur on the upper continental slope, well inshore of the 

project area. Royal red shrimp (Pleoticus robustus) are caught by trawlers in water depths of about 250 to 

550 m (820 to 1,804 ft). Tilefishes (primarily Lophalotilus chamaeleonticeps) are caught by bottom longlining in 

water depths from about 165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002). 

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continental 

Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be 

petroleum rigs offshore Texas and Louisiana. Due to the distance from shore, it is unlikely that recreational 

fishing activity is occurring in the lease area. 

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 (WCD). 

Impacts of Drilling Rig Presence 

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 

1999, a portion of a pelagic longline snagged on the acoustic Doppler current profiler of a drillship working in 

Page 148 Public Information Copy
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. 

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts 

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 ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will 

potentially mitigate and reduce the potential for impacts. EP Section 9 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 0.5 to 5 ha (1.2 to 12 ac), depending on sea state 

and weather conditions. Fishing activities could be interrupted due to the activities of response 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 (WCD) 

Potential spill impacts on fishing activities are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012b) and the 

current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with respect to 

this activity. 

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be 

interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the 

duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill 

response measures. The recent Macondo spill provides information about the maximum potential extent of 

fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010d). At its peak on 12 July 2010, 

closures encompassed 217,821 km2 (84,101 mi2), or 34.8% of the U.S. Gulf of Mexico EEZ. 

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 (WCD) are addressed below. 

Impacts of a Small Fuel Spill 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will 

potentially alleviate the potential for impacts. EP Section 9 provides detail on spill response measures. 

A small fuel spill would not have any impacts on public health and safety because it would affect only a small 

area of the open ocean 261 km (162 miles) from the nearest shoreline (Louisiana) and nearly all of the diesel 

fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with 

appropriate safety equipment to avoid injury and health effects. A small fuel spill would not be expected to 

make landfall or reach coastal waters prior to breaking up (see Section A.9.2). 

Impacts of a Large Oil Spill (WCD) 

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 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, 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, including skin contact or breathing VOCs. Crude oil is a 

highly flammable material, and any smoke or vapors from a crude oil fire can cause irritation, and in large 

quantities may pose a health hazard. 

Page 149 Public Information Copy
Data from the recent Macondo spill provide relevant information about the types of health issues that may 

occur in the event of a large oil spill (Centers for Disease Control and Prevention, 2010a). Wildlife cleaning and 

rehabilitation workers have reported concerns including scrapes and cuts, itchy or red skin or rash, and 

symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by 

some wildlife-cleaning workers. Personnel working on offshore vessels or providing direct oversight to offshore 

vessels, including USCG personnel, civilian contractors, and other responders who were exposed to oil and 

dispersants, had a 7 to 12 times higher prevalence of upper respiratory symptoms and cough than those not 

exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill 

response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from 

cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H2S, 

e.g., headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 

2010). 

C.8.3 Employment and Infrastructure 

There are no IPFs associated with routine operations that are expected to affect employment and 

infrastructure. The project involves drilling with support from existing shorebase facilities in Louisiana. No new 

or expanded facilities will be constructed, and no new employees are expected to move permanently into the 

area. The project will have a negligible impact on socioeconomic conditions such as local employment, existing 

offshore and coastal infrastructure (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 (WCD) are addressed below. 

Impacts of a Small Fuel Spill 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will 

potentially mitigate and reduce the potential for impacts. EP Section 9 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 (WCD) 

Potential socioeconomic impacts of an oil spill are discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b) 

and the current Programmatic EIS (BOEM, 2012d). For this EP, there are no unique site-specific issues with 

respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: 

it could result in extensive fishery closures that put fishermen out of work; it could result in temporary 

employment as part of the response effort; it could result in adverse publicity that affects employment in 

coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, 

including service and support operations that are an important part of local economies. 

In addition to the analyses presented by MMS (2007b, 2008) and BOEM (2012b), a recent study explored the 

economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater 

drilling (Inter-Agency Economic Report, 2010). The study indicates that during the moratorium, the number of 

oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss 

of 8,000 to 12,000 jobs along the Gulf Coast. Total spending by drilling operators is estimated to have declined 

by $1.8 billion over a 6-month period; this direct reduction in spending affected employment in the industries 

that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business 

spending (Inter-Agency Economic Report, 2010). 

C.8.4 Recreation and Tourism 

The BOEM has reexamined the analyses for recreation and tourism presented in MMS (2007b, 2008) 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, 2011a; BOEM, 2012b). 

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas 

would not be affected by any routine activities because of 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. 

Page 150 Public Information Copy
Impacts of a Small Fuel Spill 

The probability of a fuel spill will be minimized by ExxonMobil’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of ExxonMobil’s OSRP will 

potentially help mitigate and reduce the potential for impacts. EP Section 9 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 (WCD) 

Potential impacts of an oil spill on recreation and tourism are discussed in lease sale EISs (MMS, 2007b; BOEM, 

2012a,b) and the current Programmatic EIS (BOEM, 2012d). For this EP, 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 the revised OSRA modeling (BOEM, 2012b) as summarized in 

Section A.9.3 (Table 3), there is a 17% probability in winter of oil from a spill in the lease area reaching 

shorelines in Texas and a 14% chance in spring of contacting shorelines in Louisiana within 120 days. 

In addition to the analysis presented by MMS (2007b; BOEMa,b,d), recent and ongoing studies have explored 

the economic impacts of the Macondo spill including tourism and "brand" damage (IEM, 2010; Oxford 

Economics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on 

tourism across the Gulf Coast over a 3-year period at $22.7 billion (Oxford Economics, 2010). 

C.8.5 Land Use 

Land use along the northern Gulf Coast is discussed in lease sale EISs (MMS, 2007b; BOEM, 2012a,b,) and the 

current Programmatic EIS (BOEM, 2012d). There are no routine IPFs potentially affecting land use. The project 

will use existing onshore support facilities in Louisiana. The land use at the existing shorebase is industrial. The 

project will not involve any new construction or changes to existing land use and therefore will not have any 

impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal 

resources, will represent a small fraction of the level of activity occurring at the shorebases. 

A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on land use, as the 

response would be staged out of existing shorebases and facilities. 

Impacts of a Large Oil Spill (WCD) 

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A 

large spill could have limited temporary impacts on land use along the coast if additional staging areas were 

needed. For example, during the Macondo spill, temporary staging areas were established in Louisiana, 

Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease 

area, similar temporary staging areas could be needed. These areas would eventually return to their original 

use as the response is demobilized. 

C.8.6 Other Marine Uses 

The lease area is not located within any USCG-designated fairway or shipping lane or Military Warning Area. 

ExxonMobil will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by 

military vessels and aircraft. 

There are no IPFs from routine project activities that are likely to affect other marine uses of the lease area. A 

large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other 

marine uses because spill response activities would be mainly within the lease area and the duration would be 

brief. 

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Impacts of a Large Oil Spill (WCD) 

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The block is not 

located within any USCG-designated fairway or shipping lane or Military Warning Area. In the event of a large 

spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe 

operations. ExxonMobil will comply with BOEM requirements and lease stipulations to avoid impacts on uses 

of the area by military vessels and aircraft. 

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure 

that no anchoring or seafloor-disturbing activities occur near the existing pipelines and flowlines. 

D. Environmental Hazards 

D.1 Geologic Hazards 

The geohazard assessment conducted by Gardline Surveys Inc. (2010) concluded that the wellsite is free of any 

significant geological hazards and suitable for the proposed activities. See EP Section 3 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 rigs under consideration for this project. High winds and limited visibility during a severe storm could 

disrupt 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 

as outlined in the drilling contractor’s Hurricane Evacuation Plan would be adhered to. 

D.3 Currents and Waves 

Metocean conditions such as sea states, wind speed, ocean currents, etc. 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 drillship under consideration for this project. High waves during a 

severe storm could disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to 

suspend some activities on the drillship for safety reasons until the storm or weather event passes. 

E. Alternatives 

No formal alternatives were evaluated in this EIA for an EP. However, various technical and operational 

options, including the location of the wellsite and the selection of a drilling unit, were considered by 

ExxonMobil in developing the proposed action. 

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 all applicable Federal, State, and local requirements 

concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be 

conducted under guidance by ExxonMobil’s OSRP and will include the measures described in EP Section 9. 

Page 152 Public Information Copy
G. Consultation 

No persons or agencies were consulted during the preparation of this EIA. 

H. Preparers 

The EIA was prepared by CSA Ocean Sciences Inc. Contributors included: 

• C. Chandool, Ph.D. (Senior Scientist); 

• C. Kalloo (Senior Scientist); 

• M. John Thompson (Senior Scientist); 

• Neal Phillips, Ph.D. (Senior Scientist); 

• Keith VanGraafeiland (GIS/Remote Sensing Specialist); 

• Kristen L. Metzger (Library and Information Services Director); and 

• Melody B. Powell (Technical Editor). 

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SECTION 19: ADMINISTRATIVE INFORMATION 

Exempted Information Description (Public Information Copies Only) 

The following attachments were excluded from the public information copies of this plan: 

 Section 1: OCS Plan Information form – Bottom hole locations & proposed total depth 

 Section 2: Blowout Scenario – confidential information for NTL 2010-N06 calculation 

 Section 3: Geologic Description 

 Section 3: Structure Contour Maps 

 Section 3: Interpreted 2D or 3D seismic line(s) 

 Section 3: Cross Section(s) 

 Section 3: High-Resolution Seismic Lines & Top Hole Progs 

 Section 3: Stratigraphic Column with Time vs. depth table 

 Section 3: Power Spectrums and Tophole Progs 

Bibliography 

• 3D Geohazard Assessment, Walker Ridge, Blocks 191-195, 235-239, 279-283, & 323-327, Maui Prospect 

(Gardline, October 2010) 

• Archaeological Assessment Report, Blocks 237, 238, 281, 282, and Vicinity, Walker Ridge Area, Gulf of 

Mexico (C&C Project No. 120009)

• Exxon Mobil Regional Oil Spill Response Plan - Offshore Operations, Appendix H, Sept. 2011 

• CSA Environmental Impact Analysis for Walker Ridge 282, April 2013 

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